The current meta for social platforms selects for platforms that optimize for emotional engagement.
The core mechanic is "reaction", as reified in likes, shares, comments.
Posts are simply the raw material.
Reaction is what keeps people coming back. Humans have a powerful anxiety-driven need to perceive the social currents - "what are other people saying about X ?" (what should my opinion be ?)
Reaction maintains regular engagement, which allows the business of adverts to exist.
I propose a new core mechanic: Validation.
A person's social profile would showcase the posts that they have validated - verifiable record of what they judged to be true / insightful / useful.
The value proposition: That this profile would increase the user's professional reputation.
The overall result: The platform produces few posts, but each post supports a cloud of confirmations.
Highly-validated posts are then republished on existing platforms, with the validators featured alongside the author.