I can personally say from experience that there are definitely factors that limit people in their ability to play tf2/ other video games.
I used to have to take significant amounts of antihistamines because of some stupid medical issues. For those that may not know, antihistamines block histamines which cause symptoms in allergies. The side effects include drowsiness and general confusion.
My reaction times suffered greatly and as a result, I couldn't really play tf2 (or any fast paced games) well. I have some really old vods of me streaming tf2 and it's pretty hilarious to see how slow I was to do literally anything. This lasted up through early 2014, when I was able to wane off of the drugs as my symptoms disappeared (and immediately started progressing rapidly faster through divisions/ general skill). I still get spikes of these things and have to take some benadryl infrequently, and when I do I definitely notice a difference in my ability to aim, call, and react. If you ever see me doing absolutely shitty in game, this is (probably lol) why.
As someone who has played in two different mental "states", I can confidently say that it makes a difference. Some people with a naturally slow reaction time or someone who has fine/gross motor issues will definitely be at a disadvantage in a game involving so much DM and movement mechanics, and people that don't agree haven't really put much thought into it.