No one does and that’s not why Durov was arrested. It’s fine if there is crime on your system providing you are ready to work with law enforcement so that the space can be policed to the best of your ability.
If you don’t, you are basically voluntarily harming society and will be prosecuted. I’m personally fine with that.
I find it very hard to take the discussion about Telegram here seriously anyway because I just opened Telegram right now to check and sure enough the third contact in people nearby right now is called “Weed, Coke, Viagra - Buy now”. At some point, if you don’t see the issue, I think you might be intentionally blind.