Or just don't tune shit that tightly? The obsession with balance leads to a lot of this thinking. It got to the point where they were so worried about having to balance things, they just stopped adding new abilities to the game that they couldn't throw out each expansion. It used to be raids had room to address what I'll call the "main tank's wife" problem. In a social game like an MMO, it's not going to be a full roster (and bench) of sweaty parsers. A real guild is made up of a few really good players, a glut of decent ones, a rotating roster of recruits / temporary members and then friends/family of the guild. In EQ and early WoW, you had headroom in your group to bring people along who were friends of the guild and who would not normally get to see the content. You also had the headroom to still run the raid if you didn't have everyone online that night. Empty spots could be filled with basically anyone and it would be better than nothing.
They subsequently sort of 'sundered' raiding guilds by adding LFR tourism mode and the normal/heroic/mythic difficulties. Things that sound like good ideas but ended up sowing salt in the in game social communities of the game. I lead a guild for 10+ years and I could go on for hours about all the things they've done which strangled the organic development of communities. It was either deliberate or, more likely, they were too autistic to see the downstream effects of their choices.