It doesn't risk anything, exchanges are private companies and they're centralized, they have every right to list or delist whatever they want.

About a "cleansing", they could've done it a long time ago, but the thing is that those shitcoins and pump and dump cryptos generate money, and exchanges love making money so it's very unlikely that they're gonna start delisting every shitcoin in the market (that would be about 90% of the cryptos in the market). But make no mistake, exchanges do delist shitcoins every now and then, it's just that they keep popping up.

I think exchanges would rather let the market decide which coin survives and which doesn't. With BSV, that's a whole different story, there was hostility, lies, and toxicity from the BSV camp being spread around the cryptosphere and that had to stop.