At first it was all about presenting data in an original looking way. In the end it was about pushing political ideas in your throat using a plain bar graph. It was not about sharing something interesting you found but about taking advantage of a captive audience.
r/mapporn for me. Originally it was for beautiful high quality, high-resolution maps - the standard was so high that I would have been scared to post anything myself unless I found something exceptional, but eventually it became mainly low-quality (and usually inaccurate) data maps that all get mass-upvoted for some reason.
It became /r/people live-in cities
Very true. The blatant inaccuracy was the worst for me. And people usually just ignored it too.
Worse than ignore it, mostly they seemed to upvote it which is what drove me crazy. Unless there were huge numbers of upvote bots as well.
Possibly not what you’re after (fiction maps rather than non-fiction maps), but still might be interesting: https://cartographersguild.com