It's useless verbalism. Like in that koan, where a bunch of monks were asked to describe a jug, you can use all the words in attempt to describe what Photoshop

It's useless verbalism. Like in that koan, where a bunch of monks were asked to describe a jug, you can use all the words in attempt to describe what Photoshop does, but the point is, if you use Photoshop for the tasks most of professional users use it — which is retouching/design, because despite many people indeed use it for drawing, if you would talk about drawing you'd compare things to SAI/Kita instead — you most likely can not replace Photoshop by anything else without losing productivity. Why you cannot exactly do that would be a little different for every user, and that's pretty much the point — there is a thousand different things it can do, and most of them are crucial to some people, but useless to others. And something like Gimp having all of them but one crucial thing just doesn't cut it — you simply won't switch, despite it costing you significant amount of money. Because either you can work, or you cannot. And verbally specifying why is almost as much of work for Photoshop developers, as actually implementing it in code is.