That's if you want to trade in real-time, but a slow decentralized exchange still has value for casual buyers and sellers. An exchange is typically both a trading platform and a marketplace, but it doesn't have to do both to be useful.

In my opinion the frictionless exchange between cryptos and fiat will become important for real world use cases which don't need to be done in milliseconds but rather seconds

another vitally important concern in my experience is not being arbitrarily banned without any justification offered, as happened to me with coinbase.

decentralized technology has its own strengths.