Not anymore. There are plenty of pros playing at 1920x1080 with all settings on high + MSAA. High-end video cards are common as a result (as the target is ~200-300fps on 144hz monitors)
I think the reasons for this are a combination of that's what this generation of pros grew up expecting AND the rise of twitch streaming. Better looking streams attract more viewers.
There have been some investigation of settings and high vs. low generally doesn't give you an advantage or disadvantage either way.