It even bothers me that people are busy inventing new languages
which are clearly inferior to existing ones in all important
aspects.

This is not to say that people shouldn't try, but that they should
bear in mind that if they cannot claim their language is better
than Common Lisp (or at least a useful subset of it) in at least
one important way, maybe they should keep it to themselves.   It
isn't needed, and there are too many languages already.

And language designers should be able to program in numerous
quite different languages, and should maybe cut their teeth by
designing  a few special purpose languages, as I have done.

This doesn't prevent people inventing languages which aren't
as good as Lisp -- False was worth inventing, to show what could
still be done even if you limit your compiler size to one
kilobyte, for example.