Even for the same method each version of Mac OS X can behave slightly different, which causes pains for the users due to crashes and the developers to scratch t

Even for the same method each version of Mac OS X can behave slightly different, which causes pains for the users due to crashes and the developers to scratch their heads to reproduce. I've read quite a number of blog posts that the developers tried to reproduce a bug only happens to Snow Leopard. Extra code had to be written only for that. You can imagine how the code will smell if extra efforts need to be made for each version. That's the fragmentation issue I talked about and had concerns with.