Meta's platforms can require you to use your real name, give your phone number, and upload "verification selfies"/ID documents.
With federated protocols like ActivityPub (suits Twitter-like software) and Matrix (suits Discord-like software), even if one instance required the above for account sign-ups you'd have the choice to use another - or host your own and be sure that no sneaky tracking is going on.
It's true that ActivityPub doesn't really support private chats like Matrix does, and sites can be misleading about actions being visible to others (e.g: upvotes on Lemmy), but I think a protocol being designed for public-visibility content isn't inherently the same thing as it being bad for privacy.
Different instances can have different security policies too. Some will likely defederate. Many have anti-scraping measures.
One of the most pernicious things about surveillance is how widespread the tracking networks are. Different apps and different sites will embed adware that can often be connected to your account. If your social media account is associated directly with an identity like Meta or Google, it seems almost certain my posting & social media activity will be fed into the centralized adserving systems & potentially be something other adbuyers or infobrokers might acquire.
I was on Twitter to be a public person, with public words given. I still want that capabilitiy. But as @ukv says, having it decoupled & separated from the day-to-day identity I actually use, my private identity, is a critical firewall.
With federated protocols like ActivityPub (suits Twitter-like software) and Matrix (suits Discord-like software), even if one instance required the above for account sign-ups you'd have the choice to use another - or host your own and be sure that no sneaky tracking is going on.
It's true that ActivityPub doesn't really support private chats like Matrix does, and sites can be misleading about actions being visible to others (e.g: upvotes on Lemmy), but I think a protocol being designed for public-visibility content isn't inherently the same thing as it being bad for privacy.