It's not that simple though. Single-variable integer overflows can be checked like that, but when the critical byte in a buffer might be at positions 1 through {bufferlength}, you have to do a shotgun approach and see if anything sticks, and at some point the number of possible combinations grows too big even for that.

I'm not an expert on fuzzing myself, but generally I do see the point of having a limit here. Why, then, that limit was not chosen to be the max size for each of the length-checked inputs, I don't know. That does seem a bit more obvious, but also I just read this article so I can't prove that I wouldn't have made the same mistake.