I agree. PoW will always
naively be considered inefficient and wasteful. However, efficiency is relative and "wasteful" is subjective, so simply claiming that PoW is inefficient and wasteful without providing analysis is not enough.
In PoW, calculations by design take a certain period of time and that is necessary so that the numerous network nodes are synchronized with each other. This artificial slowdown obviously affects the network’s bandwidth.
The network's bandwidth is unrelated to PoW.
A tremendous amount of electricity is consumed just to build a chain of blocks and ensure its safety. Surely there have to be more efficient solutions to this problem.
Currently, most of the energy is spent ensuring an equitable distribution of new coins -- something that PoS does not have.
Another problem associated with Nakamoto’s consensus is the so-called orphan blocks. A certain chunk of the resources that honest network members spend on finding blocks is simply lost. ... This leads to the fact that some honest miners will simply waste their time and resources.
That is irrelevant. Miners are already "wasting" time and resources. The additional time and resources "wasted" due to orphan blocks has no effect on the total time and resources "wasted" due to the design of PoW.
And from here stems the problem of centralization. There are very few large mining pools and they are very large.
The danger of centralization due to pools is low. If a member of a pool doesn't like or doesn't trust its pool, then it can quickly and easily switch to another. A mining pool is only as powerful as its most apathetic members. The story of ghash.io provides an important lesson to pools that flirt with controversy. It will be interesting to see what happens to the cartel of BCH pools that are planning to take control of the BCH blockchain in May.