I think those who appreciate or advocate communism have given very little thought as to the practical application of this system, and think of only the promised gains; boy wouldn't it be great if everyone was even and wasn't self-interested, if everyone gave what they could and got what they needed--but these are humans we're talking about.
Everyone's looking out for themselves: it's how our ancestors made it, it's how their ancestor's made it, it's how every single chain of evolution down the line managed to make it: every altruistic being to have ever existed has perished as an individual entity, for those beings which were self-interested took more than those being which were not: the altruistic beings gave but did not get back, and the power gained by the self-interested organisms made it very easy to control the altruistic organisms.
Consider the history of communism: the idea, when it was first gaining traction, was that the communist society would be populated by the "new socialist man": this man, as described, would be the altruistic individual who, through cultural training, would be fully accepting of the gateway between capitalism and communism: socialism. In the societies in which socialism was attempted, in the pursuit of communism, this "new socialist man" never sprouted: it was the same old self-interested genes which every living being needs to thrive. The system was not designed for this manner of being, it was designed for some other non-existing creature, and as such problems arose: for example, in Soviet Russia--a failed socialist state--you were assigned by the state to perform a given job; people were not paid any more or less based on their performance, nor did they personally own any of the organizations they worked for (ironically), so wound up giving the absolute minimal effort required to get through the day. Usually this was not a job you particularly enjoyed; the state was not interested in you as an individual, you were simply a cog in the collective.
Performance levels of farms and factories plummeted; necessary parts to make things worked were of terrible quality, as the quotas being met were technically fulfilled, just not very well. Productivity plummets; all the capital gained from capitalism is drying up, and since people cannot simply go out in a market and fix what needed to be fixed--that was abolished, after all, along with money, and even if it wasn't abolished they were promised 'what they needed' anyway. Without a price system, nobody knows what's worth what anymore--this makes it impossible to care for finite resources: normally as supply dwindles and demand rises the price rises with it, a natural deterrent to overconsumption, but no such indication existed, so those resources were often spent frivolously, and that's compounded with poor worker performance.
The economy suffered tremendously; people were dropping like flies:
if they weren't dying from starvation, they were being killed by their own governments, dying in wars of desperation, and even being
genocided just because the men in power could. Needless to say, they had to go back to some form of partial free market activity to survive, and thus the Soviet Union is no more, and "communist" China is not communist, though its head political party claims to be, and a whole list of other socialist nations stopped being socialist; one would think socialism would've finally died there, but with the magic wand of public education, the lesson was lost on resulting generations who are yet ignorant of the horrors born from the abandonment of capitalism and its principles.
Whatever the methodology is to achieving communism, it's certainly not going to be met politically; politicians necessary demand more power to run a communist society, and the power difference goes entirely against the communist principle of a classless egalitarian society. The state isn't going to simply melt away, after all; once power is consolidated (i.e. monopolized) under one entity, why would they ever give it up? Again, the altruist loses, and the self-interested thrive. Just look at the political classes of North Korea and Venezuela: they thrive while their slaves perish.
But I'll be frank: even if communism were achievable by some other means--say, you create the "new socialist man" in a lab tube who is genetically programmed to act altruistically--they would be demolished by the self-interested people, just like the altruist's ancestors were before their lineage even got started. Altruists will always be taken advantage of, and from an evolutionary standpoint, it's a quality of weakness. A strong society is one which is full of self-interested individualists, as there is mutual respect between these "masters": a group of self-interested people create rules to help themselves--and thereby everyone else in the process. For example, if everyone agrees to the respect of each person's private property, everyone has the incentive to improve their own lives, to keep what they have rightfully earned, which vastly improves their productivity over the notion that their earnings will be seized "for the greater good." There is no stronger motivator for the base human brain than the notion that it will be overall improved.
Given this, why do people turn to communism in the first place? It is the exact same motivator: the individual believes they will gain from the promises made by communism; perhaps they envy the rich, and wish to partake in some of their wealth, their "deserved" slice of the pie--such payment will be enough motivation to make the communist system work, they imagine before ever having been through it. The individual, if short-sighted and ignorant enough, will believe there is everything to gain and nothing to lose, but the individual who is well-informed and who thinks far enough into the future will realize that there is nothing to gain and everything to lose.
As a post-script: there are many ideas on how to democratically implement a public-ownership system. The only ones I've seen which stood a chance at working out were those limited in scope to a single community (max 300-400 people.) A small, homogeneous community may very well perform better in a system of local public ownership, but this is very far from the Marxist-Leninist interpretation of a global communist system, which is usually what people refer to when talking about some kind of nationally-implemented socialist system (a stepping stone to the global communism)...one could say such individuals were...national socialists...what was the nickname for national socialists again? Well it seems they don't like the term Nazi and prefer to call themselves "democratic socialists" instead these days, but the ideas are all the same: tried and tired and beaten but still hanging on. Perhaps the Internet will help us put the idea to death once and for all.
