When CSGO was 1st released Pros struggled to get good FPS on tournament PCs. Yea the last few years they have better PCs.
I remember Shroud complaining he only had 120 FPS at a tournament because he played 1080p.
only pro players who plays the game since 1.3 or 1.5 or 1.6, are used to play with that resolution.
any other players, especially who started to play the game after csgo brand, are not used to play with it and it is not essential for them to play good.
so if you are not used to it better not to use it.
name a new, young player that isnt using 4:3 despite ropz lmao.
sergej, zywoo, frozen if you want and many more are also playing 4:3.
if you dont have the slighest clue whats going on, its better to be quiet