DEX are more secure, scalable than any other centralized Exchange...
But their volume sucks, except Binance Dex with its MM maybe.
I can not understand why launch all new and new cryptocurrency exchanges, if there are already hundreds of similar clones. Where are there so many people that would serve all these exchanges?
It's business, they want to make profits, see an opportunity and try to achieve it. But well, some of them just build it to scam and run as Vod said.