>I think there should also be a reasonable cap on the number of connections that can be made. Something like 300 friends sounds right

What about a requirement "at least one direct interaction in a year"? Maybe with a reminder "you didn't catch up with X in 11 months, are you still connected"? This will both:

* Achieve the main reason of social network existence, i.e. give people an excuse to have a chat with a former friend and keep in touch. I sometimes thing about messaging a person I knew years ago, but it feels awkward enough that I don't do it usually.

* Naturally limit the number of connections, because now having connectione require (small but still) work. A very small dopamine addicted users may still try to collect connections, but I feel like this platform will be hostile enough for them and they will leave anyway, not finding what they want from SM.