It does make sense. You need to think a little deeper than this "stop carrying/never carried" distinction on which you're so hung up. That's relevant, but it's not the entire issue.
There certainly has, with respect to flagship products, of which the apple watch is one. Apple does not and never has sold desktops, laptops, smartphones, tablets, or music players that compete with their own.
Not if you're trying to evaluate whether Apple's decision is rational, or whether it's "anti-competitive," as many in this thread have claimed.
It absolutely does. You think that distinction is the whole ballgame, but it isn't.
I don't agree with that at all. There could be perfectly rational business reasons for saying "we're going to sell someone else's iphone cases but not someone else's smartphone." The most obvious reason being that every case sold implies an iphone sold (either to that buyer or to the recipient of a gift), but every Galaxy S6 sold does not imply any other sale beneficial to apple. Another being that Apple isn't really making their living on iphone cases; if they make a few bucks that's great, but they mostly sell them because it's something iphone buyers want, and they make their living on iphones.
Any examples other than minor accessories/add-ons? I can't think of any. As I said, certainly not any desktops, laptops, smartphones, tablets, or music players. The apple watch is, like those products -- but unlike a case or adapter -- a "flagship" product for apple. So yes, this decision is entirely consistent with their principle of not selling against their flagship products.