Play what you want, and do M+/raids with guildies, not pugs. I'm good enough that 5% isn't a big deal at all, as I can outdo a lot of the other combos despite what simcraft says, and I've been with them since Vanilla. I actually pre-date the current GM.
Having said that, they're not pushing bleeding edge mythic or M+. They'll get there before the next patch, but they're not pushing that hard.
If you're in a min/max guild, be prepared to do what you're told, and do it the way you're told, or not get to play. You *do* have a choice. Leave that guild...or deal with the consequences of where you are. Or try to pug raids and M+, and let Raider.io rule your life, of course. I won't do any of that. YMMV.