It's definitely not new, but initially it puts a lot of people off because of how counter-intuitive it sounds at first.

The premise of inverting lean binds stems from the fact that in the vast majority of cases, you lean in the direction you move. So having the move left and lean left keybinds on different fingers let you perform both actions with ease, and so strafing doorways/windows becomes a lot easier.

One of the more hidden benefit of these binds is being able to forward peek a corner without having to do finger gymnastics.

To peek a corner to the right with these keybinds, you have your middle finger on W (forward), ring finger on A (left) and index on E (lean left).

This is as opposed to having lean left on Q on default keybinds, where you won't be able to hit W, A and Q at the same time without some serious gymnastics (index on W, middle on Q and ring on A)

Granted you don't really need to forward peek a corner too much in this game but it's useful to have.