[mort96]

The point of a bump allocator is to be short-lived, and to be incredibly fast. You want to be able to make a bump allocator with a fixed buffer, pass it to some code which takes a generic allocator (and therefore will call allocate and free in any order), and then free all the memory in one shot at the end. If calling free out of order made it throw, it would be useless for that purpose; it would only be useful for code written specifically to use a bump allocator.