I don’t think it’s good form to downvote people you disagree with.

I did not downvote, but I'm guessing that it is perceived as disrespectful to call them failures to the point where they don't even qualify as "alternatives".

The word "failure" was never used.

But, they are technically correct. The language is defined as by CPython: it is the standard!!! None of the others fully meet that standard, which includes quirks! It's knows trade offs with them! They are, literally, attempts to adhere to that standard.

It’s no slight to jython. They fill an important Niche. But jython will never ever be confused with python.