Well, if by “open source” you mean broadly any software available whose code is viewable on the internet, you’re essentially advocating for no projects that use “nonstandard” licenses to exist.

That seems like a waste if there would be otherwise be projects around with a nonstandard license that was acceptable to a subset of users.

For example the CPython interpreter (the official interpreter for the Python language) does not use a standard license. Would you not want Python to exist?

Any permissive software license (which it seems CPython's is) is broadly interchangeable with any other, and can be used with both other permissive licenses and copyleft licenses like the GPL. That can't happen with any license that places restrictions on what it can be used for.