Lately I feel more value in connecting with them personally, talking and letting them now, that I am still interested in what's going on for them.
Social media is how I keep vaguely aware of what's going on with my friends who now live scattered across the planet and get to see in person once per decade or so.
At most, you can call them professional contacts whom you hope to get some value out of in the future, and in that sense I’d agree — social media makes it possible to keep in touch with people whom you have a transactional relationship with.
And all of them are relationships with someone I already know, can ve safer around then random and some of them grow again into more active friendships in right situation.
And yes, that friendship happens again thing is real.
I suppose the app will then mostly be full of throwaway comments in the form of "Cool" or "Wow". But maybe add a modifier that if the poster doesn't have any meaningful reply to a commenter's (let's name him Elon) comment, then the poster's next content will not be shared with Elon next time.