[antonvs]

I’ve never used any of the ones you mention, aside from LinkedIn as you say.

There are different reasons in each case. E.g. Twitter’s short message limit seemed guaranteed to produce what it did, compared to e.g. Usenet or HN. Facebook originally seemed to me like a way to publish on the web for people who didn’t know how, like Geocities. MySpace seemed to be for teenagers. All of these were reasons not to use them initially, but over time nothing changed in a positive enough direction to change my mind.