i have never liked them. the idea of masternode is a terrible one and is basically leading the coin towards centralization! the whole spirit of cryptocurrencies is their decentralization and the fact that you use them in a peer to peer manner not "peer to server to peer" which is the old flawed centralized solution.
not to mention that the risks that they have for those investing in them since you have to lock a large sum of money in that coin in your master node if you want to run one, and risk losing it to hacks, bugs, and on top of it all risk the price dumps to lose a huge amount of money!
With regards to how Dash implements masternodes :
Centralization accusation
Almost 5000 masternodes spread over different geographic locations :
http://178.254.23.111/~pub/Dash/masternode_locations_stats.html I would not call that centralized, i would call that decentralized. Also with Dash annual -7.1% reduction on its blockrewards for miners and masternodes, decentralization will only increase over time.
On a sidenote : in crypto pretty much all cryptocurrencies have centralized aspects, as the whole market is still in such an early adoption phase.
Locking money accusation
You dont lock a large sum of money, you put them in a cold wallet / hardware wallet so its safe from hacking/ theft and if you want to cash out you simply move those coins to an exchange.
No locking involved in any way and you remain in full control of your Dash at any time. Of course when you do move those coins to an excange, the network will not regnonice your server as a masternode anymore and you will not receive any further payments.
Peer to Server to Peer accusation
Masternodes are not different from Bitcoin's full nodes, except that owners get rewarded for their masternodes staying online 24 hours a day while providing support for its additional services like InstantSend and PrivateSend.
Which means Dash is just as peer to peer as Bitcoin, except that Dash has unlocked additional decentralized services which Dash can run on top of its first layer (miners), which Bitcoin cant.
Bitcoin tries it though through the development of its Lightning Network by implementing sidechains, but thats centralization at its best and funds in those sidechains actually will be online, vulnerable to ddos / hacking / theft and most importantly : not directly under your control.
Vulnerable to price dumps accusation
Price dumps (and pumps) happen to every cryptocurrency and to every large investor. Some Dash investors choose to cash out to FIAT, some choose to convert to a stablecoin but most masternode owners just keep their investment in masternodes, saving up their
masternode payments in a bear market and cashing them out in a bull market in a pretty much risk free way.
The continued increase in number of masternodes shows that Dash investors have a lot of trust in Dash ability to continue its development, survive bearmarkets and meet its goals, while at the same time providing the network with a very strong full nodes network.
Link :
http://178.254.23.111/~pub/masternode_count.png