To my mind, one of the disadvantages is that decentralized exchanges, if we take exchanges as an example, have lesser pool in comparison with centralized platforms. Furthermore, for a cryptocurrency to be presented at the exchange, it is necessary to employ a smart contract, and not all of them use it.
I'm sorry but your are out of topic, we are not talking about exchange, we are talking about the decentralize system as a whole, like the blockchain.
Decentralized System's biggest Disadvantage is to allow some illegal transactions to continue in the dark corner, because Decentralized System excludes regulation, and we all know that anything that is out of regulation will be used by the bad guys.
You said it right mate,the dark side of the centralized crypto community is one big factor why the disadvantage occurs without regulation this can be use in many bad aspect such as fundings the terrorist or used as payments for illeg Transactions like gun running or drug trades
So you are saying that fiat is not use for funding terrorists and illegal transactions, regulation does not solve it but will minimize this kind of activity from happening. I will still vote for the blockchain to remain and be successful, give that task to the government if they want to regulate, as long as it will not change the technology which is decentralize.