It's a debate that has been violently splitting the Fortnite community for months: is it necessary to nerf controllers aim assist? Epic Games has decided to remove Legacy controls setting as of March 13. Please note: this isn't about removing the aim assist as a whole.
In short, the legacy controls setting is a long-range aim assist, which allows you to spot enemies through walls or wheat fields by alternating 'L2' and 'R2' very quickly. A manipulation considered "unfair" for all those who play with a keyboard and a mouse. On social networks, many clips highlight the omnipotence of such a feature.
The linear aim asisst — which will still be present after March 13 — only concerns very short ranges. It's not a total dissolution of the aim assist that we have to deal with, but we have to admit that Epic has taken the bull by the horns, by attacking the right source of the controversy!
It should also be pointed out that the "controller community" is more numerous than the keyboard/mouse aficionados. Epic Games can't make too many gameplay changes without risking an outcry from its largest community.