I'm not really sure what your point is. The point is ASCII/UTF-8 are a binary representation that is easily parsed by humans, which is why we use it for writing code. Sure, if you want, dump both files with xxd and do a diff on that instead.

There's been ways to diff binary files forever. Doesn't mean it is a great idea to store source code in that manner though. With UE4 you're not really supposed to be able to edit the Blueprint "code" outside the UE4 Editor.