> Of course there are ancient, rarely updated guidelines
You mean well researched guidelines with tons of evidence behind their decisions [1] that are as relevant today as they were 20 years ago.
> almost all applications ignore.
That most current applications ignore because people think they are ancient rarely updated guidelines.
This is especially evident in the MacOS world. HIG were the guide on the platform, and developers tried to adhere to them. And then the new breed of "designers" took over and even Apple breaks nearly every single one of them [2]
Microsoft has always been worse when it came to enforcing consistency of user interfaces, but even their choices were never random until quite recently [3].
[1] Apple's original HIG even had a bibliography section because it was actual research, and not some Dribble showcase: https://twitter.com/andy_matuschak/status/144740917559669965... and https://twitter.com/andy_matuschak/status/144771024771228057... etc.
[2] See, e.g. their abomination of an App Store https://grumpy.website/post/0RsaxCu3P
[3] Even the ribbon menus they introduced in Office weren't a random choice. They surely are now. See the Why the UI blog series: https://web.archive.org/web/20080316101025/http://blogs.msdn...