That is a nicer message than I remember. I don't have an issue with that. It let's you know it doesn't work, that it will never work, and provides links to an alternative and more information.
It either used to do fewer of those, or my memory is Swiss cheese, but I remember needing to search for the why's and alternatives.
There was a period when the error was a stack trace. But that was pretty brief, and happened before PyPI moved more "officially" towards not supporting the search API.
I think part of the confusion here (which is reasonable IMO) is that pip has a huge version tail, and so people report error messages and behaviors that have been fixed for years. This is one of the challenges that I think gets under-appreciated about pip's maintenance.
It either used to do fewer of those, or my memory is Swiss cheese, but I remember needing to search for the why's and alternatives.