Because of government pressure. It was delisted by lots of exchanges purely based on government fear of privacy and independence, not any technical or demand reasons.

The CEX that do list it, it is essentially a trap. As soon as you do something with XMR they start freezing your account and demanding all sorts of KYC/AML. That is my experience after playing with it by pulling out a couple hundred $ and doing nothing with it other than putting it back on an exchange.