I get that it’s well intentioned but I wish folks stopped talking about the buddy allocator. It’s so obsolete. It’s not the fastest and it sure has some of the worst fragmentation due to very imprecise sizing.
In any case, the glossary is up front about their disadvantages: https://www.memorymanagement.org/glossary/b.html#term-buddy-...
IIRC, Linux and FreeBSD both use a buddy allocator for physical memory, and I'm pretty sure it is used (in addition to other allocators) in jemalloc as well.