But this does not mean Kucoin is not a centralized exchange, they can decide to freeze customer coin or seize it or lock customer's account and tell customers request for KYC. You are not wrong that some people can still use Kucoin to trade without being verified but Kucoin have the ability to overide customers decision because it is still also a centralized exchange.
FTX is for future trading with a large amount of money. Kucoin is for trading any altcoins that aren't listed on Binance. The future trading on Kucoin is really bad, the indicator and function so confusing, not to mention the market volume is so little as well.
FTX has high marketcap than Kucoin, that is one of the reasons, I have preferred Binance and OKX for future trading, I registered on FTX through the mobile app and it was a worst experience for me until I later decided to open OKX when j was looking for another alternative to Binance.