Huge swathes of features appear at transition points like MySQL 5.5 -> 5.6, which means lots of answers are now viable but no longer the best option. And since they are still correct, it's hard to write up new questions which won't be closed: instead of saying "Answer X no longer works", users have to say "Is Answer X still the best approach?" and get closed for duplication or subjectivity.
Worse still, lots of databases still have multiple versions in active use, so "worked great for me! - posted yesterday" isn't even a helpful reference.
Microsoft's decision to drop those technologies from Edge was kind a mixed bag. From a security perspective it was the right decision. But it has also stuck many of us developing for a non-evergreen browser, even while our users are on Windows 10.
IE11 is the new IE6.
I think Microsoft has made a mistake by stopping the addition of standards-compliant features to IE11. They should keep supporting it and modernizing it until the userbase has moved to Win10 on its merits, instead of trying to use IE11's aging as a lever to force Win10 adoption.
I do think a mistake was that IE11 was included at all in Windows 10 to appease corporations, instead of just ripping off that particular band-aid. But doubling down on it and allowing corporations to default to nothing but IE11 via group-policy is the biggest mistake. GPO footguns like that are why corporate America can't have nice things, and I'm increasingly of the opinion that it's time Microsoft started dropping footguns from GPO.
(Also, note that the root problem in this particular workplace remains Oracle and their web apps that are stuck in IE6 worst practices but cost millions of dollars each year to continue to operate. Oracle is the real villain here.)