I have disabilities (anxiety being one of them) and I don't mind the new content (barring the first boss in the Deadwalk dungeon, that one I have issues with). I still raid savage and ultimates (granted not in HC), and actually enjoy the challange. I have learned ways to make my disabilities less impactful on my play, like using controller to keep my back from seizing, adjusting rotations a little bit to keep my hands from cramping (to much weaving causes issues for me), and knowing which mechanics will cause a freeze reactions for me and thus having to use a follow the herd tactic to get through it. My numbers on the forbidden abacus ain't great, but they are decent. I have cleared 6 raid tiers on content, and 3 of the older ultimates on top of it. Almost made it through DSR before my previous ult static disbanded, so found a new one and looking forward to redoing TEA with em soon. So disabilities are not an excuse, even though it makes things more difficult.
I had a feeling that some of the more casual people out there would have problems with the new content, but it's still doable if you pay attention to the new telegraphs. Damage is survivable if you use your mitigations, which I saw a lot of low mitigation usage during previous expansions.
Also it's new mechanics not seen before, which always will cause people to take time to learn them. Just keep at it, don't be afraid, and be prepared to use your kit