In the old days, these different OS would have separate teams and all trying to work on what is best for their own products. Be it mac, iPad, iPhone or what hardware it is.

The foundation may share resources, but everything else was tailor made. And that is what used to make Apple so good.

The moment you try to make one size fits all you will start to make compromise. And the good old Apple would try to do things the hard way rather than making unnecessary compromises.

It is sad.