Blizzard try as they may, they always seem to shoot themselves in the foot. They make every class easier to play but because the gear gap has never been higher, it is a complete nightmare catching up, especially on a pvp server. This is because the combination of artifacts, legendaries and gear cause such a power spike, it feels like you're level 5 by comparison. Raid tanks can literally solo 4 middle end players with minimal effort, simply because they take 0 damage but deal almost as much as a dedicated dps.
I'm seeing all kinds of stupid **** that should never happen, like 920 dk tanks outhealing 880 healers, 920 healers outdamaging 880 dps and so on. Have fun trying to catch up in Mythics, you will have to do +2-5's for an eternity before you're ready for +10-15. Just so many bad gear design choices that casts a fog over any positive changes they might have done.
I've been playing WoW since launch and have never felt further behind than I do in Legion, and that's with the artifact catchup mechanics in patch 7.2. I can't even imagine before. If you don't already have a character in Legion, my advice is don't even bother.