While generally I think that your approach is the best approach to discovery, I think it is prone to privacy complaints. I’ve certainly looked at… things… on social media that I wouldn’t want close friends or family to get recommended to them, even worse if they know they got recommended it because of me. Not everything everyone interacts with on a social media platform is meant to be shared with everyone else.
I think that problem is relatively solvable though: giving people privacy controls and making operations that are public explicit is easy enough. Like, if you are commenting publicly on something, I think it's fair game to default to showing that to people who follow you. OTOH, it doesn't have to be forced to work that way. Heck, Twitter probably did this right a long time ago: if your post started with an @ it would not show up in other people's TLs, making direct replies not show up to your followers; but if you add a dot at the beginning, they would. Now obviously that's unnecessarily arcane, but at least to me the concept of being able to control that would be a good start. Combine that with a good system of identity where users can change their publicly displayed identity and work under multiple aliases fluidly and this should make it possible for people to manage things decently. It's odd how Twitter actually was kind of close to this at a point; it has fluid identities, they added the ability to switch between up to five accounts, etc.
Then they screwed up by surfacing likes and never adding an option to make them private. Very dumb.
