tbh Mei has been out of the (proper) meta for a long time, as had junkrat. It's interesting how almost all the area denial heroes are called 'cancer' because they force you to adapt your play style (junkrat, mei, sym, torb). The issue I feel is not the heroes, but the fact that nobody in matchmaking plays as a team in order to work around them properly. There's a reason you don't see most of them in pro play (junkrat being the exception, but that's because he's now a bit op)
Discord