I wouldn't say any language, but yes,

replace it with Haskell, Ocaml, probably Erlang, and it would probably work:

Why is language X still not popular after Y years?

Because quality and good practice are expensive.

Hidden in this statement is the assumption that all mainstream languages and all mainstream language programmers are low quality and they only follow bad practices.

Disregarding its arrogance, the statement is just false :)

> all [..] only

It implies nothing of the sort.

> quality and good practice are expensive.

That's the statement. If that implies to you that it's impossible to achieve quality and good practice in any but the aforementioned languages, feel free to do so.

> :)

:)