I think they had some plot, but it seemed to be very heavy on sex scenes. I didn't read these stories, this is all stuff I'm hearing on Wattpad discord servers I'm in, Twitter, etc.
I'm not an avid user of Wattpad, so I wouldn't know how long the censorship issues have been going on.
You are right on the popular stories getting a free pass though.
Either way, I think Wattpad's content guidelines on mature scenes are a bit weird. It basically says you can write sex, but not only sex. If that makes sense.