Hijacking native scroll behavior to badly reimplement anything remotely like scrolling is wrong even in a gaming context. But if you're implementing Half Life 2 in a browser, where the user no longer has a normal cursor, then hijacking scrolling to implement the weapon switcher is fine.

Yes, that. Or some weird experimental stuff, like running an emulator for the Playdate https://en.wikipedia.org/wiki/Playdate_(console) or whatever. Games are allowed to be a bit wacky, and no one is forced to play them.