This seems to fail to understand that we already have both levels.
Every OS will provide some mechanism to get more pages. But it turns out that managing the use of those pages requires specialized handling, depending on the use case, as well as a bunch of boilerplate. Hence, we also have malloc and its many, many cousins to allocate arbitrary size objects.
You're always welcome to use brk(2) or your OS's equivalent if you just want pages. The question is, what are you going to do with each page once you have it? That's where the next level comes in ...
Every OS will provide some mechanism to get more pages. But it turns out that managing the use of those pages requires specialized handling, depending on the use case, as well as a bunch of boilerplate. Hence, we also have malloc and its many, many cousins to allocate arbitrary size objects.
You're always welcome to use brk(2) or your OS's equivalent if you just want pages. The question is, what are you going to do with each page once you have it? That's where the next level comes in ...