this used to be a playstyle many years ago, but nobody uses this playstyle anymore. today everyone uses the playstyle called "spread" where you use 2 fingers on each hand, traditionally your middle and index finger, and use keybinds which are spaced out, like qwop or asl; or zx,. etc
edit: also worth mentioning that the reason nobody uses this playstyle anymore is because it severely limits the maps you could play. the maps you can play with index (how this arrow playstyle are called) are mapped like garbage and are very rarely made anymore. everyone uses spread because it works with all maps