Rather often... though this will be a point of contention I am sure but I would argue it has always been the case. Even now with a perfectly geared raid team some specs have less then 100 players clearing the raid on mythic and judging by the logs a lot of those are people buying a carry.
WoW has never really been a game that allowed or rewarded experimentation at any point at the high end (for the sake of this conversation high end being full clearing or 2400+ mythic 25+). You can argue that its always been a thing in normal mode and before that the starting tiers of each expansion but to pretend it was ever the dominate playstyle of the game much less a viable one is highly suspect.
I will freely admit I honestly don't believe this invisible minority who wants a personalized character actually exists in wow. When it did exist via raid legendary items like windfury, shadowmourne, whatever the staff, hammer, and daggers were call players who couldn't get them screamed bloody murder.
I sympathize with players who want to stand out in the game. So far the only real way to do it is to excel at one of the hardest aspects of the game but I don't think this experiment is going to end well for anyone.