They say cool URLs don’t change, but a lot of the time you don’t get a choice. Google decided that http wasn’t good enough, so bluehost (my hosting provider for this blog) switched me over to https automatically. Then I got to have the fun mixed content warning on an older post that had an embedded image in it. At least they put in redirects.
Now my old university hosting has decided to close off AFS access to alumni. So what? Well, personal web pages are served from AFS, which means the small handful of things I have over there will start 404ing, without even the opportunity to put a 301 redirect on them. (I just noticed that they have changed the URL there too, but with redirects. So now there are two URLs that will go dead when they throw the switch.)
Sorry w3c. Cool URLs might not change, but my providers require me to be cringe.
(Not that anyone links to a basically dead blog anyway, but I was trying to be a good web citizen.)