I think it is because, for a lot of people, Lisp is fun.

If Lisp flourishes, more people would get to use it at work.

Lisp not flourishing means less fun.

Also, when I've worked in Lisp it just seemed like the right way to do things. Everyone likes to do the right thing, so anguish results when you seem denied the opportunity to follow the path you feel is right.

That said, I think the author was right and the community issues and ease of building your own solutions will limit Lisp as a language family.