It’s a really hard problem for devs because spammers can use AI to create profiles that are practically indistinguishable from regular users. The fake profiles could be filled in complete with avatars, background image, etc. 

Imagine if every post with hit with 100 replies that you’re pretty sure aren’t real but you don’t know for certain. 

Spammers will use TOR and VPNs so if relays block those, they’ll harm the privacy of real users. (Eg I’m using TOR right now)

Spammers can also target larger accounts or new users for abuse and can also flood your DMs with spam to make that unusable too. 

It’s a hard problem. No easy solutions. I’m personally in favor of the WoT model with a guided onboarding process for new users to get into the web of trust.