I'm not sure I totally understand what you're saying, but I'll try to respond: When Apple bought NeXT and Steve Jobs took over as CEO, the OSX project was born

I'm not sure I totally understand what you're saying, but I'll try to respond: When Apple bought NeXT and Steve Jobs took over as CEO, the OSX project was born at that moment. Before that Apple had been stabbing wildly in the dark for a solution to their outdated OS, with a bunch of failed efforts at a rewrite. Yes, they updated the old MacOS a couple of times, which needed to happen, but as soon as OSX was ready for prime timee, they made the switch. iOS is to some extent based on the same internals as OSX, but even if it were a completely different architecture, I'd say it's actually a good example of Apple's focus. Rather than forcing crossover and synergy where it doesn't make sense (ie, forcing the Metro interface onto the desktop and server, without actually providing Metro interfaces to their most popular desktop apps or server tools), Apple created separate OSes for devices that have completely different roles.