Look at the pro basketball players and compare their body to yours. If you are changing your body to look more like them then it will probably help you. At some point muscle will hurt performance or else pro basketball players would look like pro bodybuilders.
You’re close, but still wrong.
It’s not that “muscle hinders basketball performance”.
It’s that “playing competitive basketball strongly impedes muscle growth”.
Playing a season of competitve basketball and building muscle mass are nearly diametrically opposing activities. THAT’S why basketball players tend to carry little to no muscle mass.
Nearly every single player in the NBA would benefit from putting on a few pounds of muscle. The problem is that they don’t have a lot of time between seasons to devote to muscle building (they HAVE to spend a good portion of their off-season recovering and healing from the previous season), and what muscle they might have built would likely be lost over the course of a full NBA season.
It’s also true that most players don’t need a lot of muscle to be successful, but having more muscle would most definitely NOT hurt their performance.