Whose idea was it to block players from entering pvp matches after they start? Do they think it’s fun to completely miss GvG and TBL matches because of crashes or disconnections before joining? Well, perhaps that is the ideal solution to low framerates: stop people from playing entirely. It’s common to have half a dozen people crash in the middle of a GvG match because of known bugs, and none of them can come back in.
It’s not like they need anything more to discourage people from doing pvp after the ranking system got bugged and stopped updating.