Yeah but there are definitely different levels.
That's why you don't "know" kung fu, or "know" boxing; you keep at it. Which, in the belt granting world means something very different than actual progression, and why we live in a world full of black belts that are, to be honest, terrible at martial arts but talk a lot, while legions of sports people actually train in hand to hand combat (and get told off by those same "street rules" black belts).
I'd even argue that the entire BJJ phenomenon is more or less a reaction to this. A bunch of guys that were really, really into Judo and Vale Tudo saw the world filling up with kids imagining they are masters and getting black belts young.
There's keeping it real, and not, and I think we can both agree the vast majority out there do not.