> And then, as others have mentioned, it's hard to find Lisp programmers. Most programmers are turned off by the [...] immutability.

Most Lisps have very little in the way of immutability (except for C-style "undefined behaviour if you modify it"). They tend to be very dynamic, living systems, and making everything mutable is one way of enabling that. Some people favour a functional style, and a functional style is more common in some dialects like Scheme, but it's almost always essentially "imperative code with good support for higher order functions," and most Lisp programs have always mutated state freely.

There are exceptions, but they are exceptions.