Look, consumer electronics these days are for everyone (they're not like the Casio calculator watch from back in the day), so they need to look sexy and even a little bit "exclusive". Apple hasn't been "exclusive" for years now, and I suspect they want to take the idea back a little: being fashion-forward AND having something that not everyone else has yet.
Except...I've had a smart-watch for months. People notice and ask questions, but I've observed that the questions I get aren't from people who WANT one of their own, even the iPhone users (people still have phones that are glued to them anyway), they're just wondering why I have it in the first place. So Apple is probably limiting supply to increase perception of demand.
Or they're limiting supply because supply is limited, which has been known for some time.
Of course, the click bait summary doesn't think that's a sexy enough headline, so they're going with the "exclusivity" angle.
If you walk into the Apple store and want one, an employee will walk you through buying one online fem inside the store, because they won't have the stock on hand to just be able to give you one right there due to a) the tight supply of the watch itself (mainly down to the screen) and b) the large number of combinations of strap.
Until the demand settles out, you'll have to order one online, which is exactly what Apple are setting up for. Either ahead of time and then pick up in store, or if you just walk in, they'll do it for you right there.
However "Apple employees will order a watch for you online if you go to the store because they won't have lots of stock on hand" just doesn't get those ad impressions roiling.