This would have to go hand in hand with better user authentication and biometric login but I didn't mention that as there's no novelty here. But for example try writing a bot that creates Facebook or Apple accounts and you will quickly find its not trivial.
Right now, twitter, reddit etc actively encourage bots that are deemed useful in someway such as auto moderation bots and gimmicks like the gif reverse bot.
My argument is essentially for a service which decides the good bots are not worth the bad and dedicates some resources to shutting them off.