Fact of life: the vast majority of your users do not read your documentation (or do not do so carefully enough that what you put in your docs is an ironclad proof that all users adhere to). That's literally what Hyrum's law is about. Of course, you can choose to do whatever you want. It's valuable to recognize of course that you're trading off good will from your users with whatever technical improvement is getting made. Sometimes it's appropriate and inevitable (e.g. old behavior is just wrong or harmful and better to cut off). In the vast majority of cases though it's better to just have a better process in place to manage this with minimal disruption, identifying and communicating with broken users, and only then making that change.

You just described >90% of users. Everyone does this for something, most people do it for most things.

You minimally read the docs, get something working and then leave it alone. Of course you're going to be pissed off when an implicit assumption which has been stable for a long time is broken.

I don't think expecting users to go look for a user manual on each website whose links they download from is a realistic expectation.

If you don't want users, feel free to ignore them.

If your product supports some particular behavior, it will be used regardless of what you document.

Microsoft was once renown for bug-compatibility so as not to break their users. The new wave of movers and breakers would forget that wisdom at their peril.

Give a man a fish and he’ll assume he’s entitled to a lifetime supply of free fish.

This. You have to draw the line somewhere. Was this specific choice that line? Maybe not, but sometimes users aren’t right and changes just need to occur to ensure other asks from the same users can be delivered.

I'd imagine they broke their own stuff doing it, considering npm broke on it

Do you work for Google?