It’s just that often they are not, and both good and bad design comes without a decent manual.
It feels to me like it happened around the time of the first iPad. That was such a usable device (and OS X was just about at its peak of perfection at the time) - I remember just opening the box, turning it on, and everything being intuitive. I’m 99% certain scroll bars were still present then, for example.
I don’t think we ever really made the transition from paper manuals to online help very well. Some apps need additional help, and some even make it available, but I rarely see people-in-need actually making use of it. Heck, they rarely even consider googling for help (the issue in the article can be worked around, at least, with a google search). At least with a physical manual, you knew how much help was available/necessary for a given app - that’s just not the case with 'software help' or help online.
My C=64 came with a thick reference manual, with circuit schematics in the back. Every computer I've bought since then has had a smaller manual. I think my smartphone came with a small pamphlet with a couple screenshots.
It seems you're supposed to learn how to use electronics these days by having people say "oh, don't you know?"