But, that's what restrictive means. They are designed to do things in a particular limited range of ways that do not generally overlap with other combat roles.
No, you're describing prescriptive, and not descriptive. I can describe myself as intelligent, handsome, charming, articulate, and always right, but that doesn't mean that there's nothing else to me; I'm just pointing out my strengths
When I describe an ogre, if I describe it as a "brute", we know that it's good at hitting things and taking hits. It doesn't mean it can't throw or shoot things at people. It doesn't mean it can't try to sneak. It's just talking to the strength of the creature in that particular role.
Thus, make the creature, then describe it with roles, using multiple roles if appropriate. Descriptive, not prescriptive.
The slogan of combat roles should be something like, "This is how we designed these to work, but play it anyway you like.

"
I think this is incorrect, honestly. You don't have to assign a role before designing a creature. I could go through the 3.5 MM right now and describe them via a "role" if I wanted to, and many would be one role, some would be two, some would be more. But, here's the thing; it's just easy shorthand. And, for people that want to make their own monsters, they can still give guidelines on how to use them in a prescriptive manner,
but it's not necessary. They can be just
description. As always, play what you like
