Liberals have nearly the entire internet as a safe-space. It's nice to have a community with similar views, especially political as people are always just looking for confirmation bias, not really willing to debate, so it's too toxic to try all the time.
That's not what a brigade is.
> To my knowledge there was no coordination of all users to brigade.
I was in the Discord and an active member during the 2016 election. It was actually really civil, more-so than other political subs. Outsiders aren't as welcome as supporters, but try to be a Trump supporter in the /r/politics sub.
tl;dr There was no brigading by T_D, Reddit just didn't like conservatives using their site. Post proof if you have it, otherwise I'll go with my experience with them.