I am actually trying to get caught up to speed on this as we speak. I don't like sounding dumb in discussions which has happened a few times on here it seems lol.
Unless you can replace the W-L record with something similar, it will remain in the game. People like to know what are their teams chances are when a particular player plays. They could be kept for every player and they kind of are unofficially. We've all heard the "team is 15-5 when play X players."
Very stupid stat on its own for sure but with gambling blowing up, casual gamblers/fans just want the dumb downed version of what they can expect the outcome of the game to be. Unfortunately, the people who place betting lines use more complicated algorithms than that lol.