Toxicity apart, the reason ( and I chose to use the word reason instead of problem/issue, because it's something which is related to simple aspect of the game ) is that players take for granted that everybody knows which is the meta tier, and he has the right class for the right encounter. Given a specific challenge, the players will try anything to lower the difficulty of the encounter, which includes: Using voice chat.Using the best build ( Profession, equipment, infusions, food, etc ).Class Swap if needed ( everybody, since the game throws you equipment aoe, many players could bring support to party just by having more classes, and by knowing how they work ).Recruit for the run only experience players ( with many tokens ).Etc...If you go not following this pattern, there's a higher possibility of losing time ( because of wipes, due to low dps, low heals, etc ).And since the raid is made for up to 10 players, think what could happen if anybody try to play the way he wants. At last, this is not a criticism.I just explained what players want in order to save time and lower to increase to the top the chance of success.