Why do pro players use low resolution?

[xDzenoX]

So recently I started following pro scene and I noticed that most of the players play on low, 4:3 resolutions. And my question is why?
I get that most of those players played 1.6/Source and got used to 4:3. But even some younger dudes like Scream (born in 1994, I doubt he played much on 4:3) prefer that. I know that low res=more fps, but srsly you can run this game on potato and still have 60fps. Also they play on a high end PCs anyways, you can probably run Crysis 3 on Ultra Uber High and 4k on those PCs. I've also read that low res and low texture details means less distraction and bigger hitbox, which kind of feels like cheating, well not cheating, more like an exploit.
But isnt it better when you're in 16:9 and have wider view?

[KillahInstinct]

You can also see more.

[ithie]

bigger pixels, easier to hit the hitboxes

[Xuxi]

Bigger pixels, old players (old monitors 4:3) and all tournaments use differents monitors with diferent res so they use 4:3 for the same in all monitors.

[you again!]

I don't know about the low resolutions, but CS:GO is what's known as a "Vert-" game, which means that widescreen resolutions cut off the top and bottom of the frame (as opposed to "Hor+" games in which widescreen resolutions extend the field of view). Therefore you get a higher field of view (vertically) by choosing any 4:3 resolution.