Huh? This sounds like you mean before elon "free speech!" musk but I can only imagine that, if it ever was a thing, it was a thing after. At some point a competitor's links were being blocked, a little 'oops'ie with 'the algorithm' of course. Facebook also pulled some of those over the years. I don't know about outright bans though, especially concerning Twitter before Musk
> "We know that many of our users may be active on other social media platforms; however, going forward, Twitter will no longer allow free promotion of specific social media platforms on Twitter," the company said in a statement.
https://www.pbs.org/newshour/economy/twitter-bans-linking-to...
https://www.nytimes.com/2022/12/18/business/twitter-ban-soci...
that's precisely what I assumed
Genuinely thanks for doing the effort of looking for sources and correcting someone you thought was wrong, but the allegation of me singlehandedly (just the thought! :D) trying to rewrite history maybe goes a bit far when I said it was just my assumption and that I don't know of such a thing before elonmusk took over