> Apple and Google will probably do something similar with their various operating systems, but Microsoft has managed it first.

I thought all of Apple's OS variants these days were based on the Darwin kernel and variously intersecting sets of the same unix components and APIs. Every now and then I see someone complaining that a new Apple device contains 'an entirely new OS' like Apple TV OS, but isn't that just a variant of iOS? It seems to me it's precisely because Apple have been determinedly pursuing this common core stragety ever since the first iPhone OS that they've been so successful, compared to Microsoft's strategy at the time of having completely different code bases across product categories.