I think that's backing up the point he's making, though. When considering the big picture, tiling window managers are quite minor and relatively infrequently used.

Having a small amount of influence within a rather obscure field ends up translating to basically no importance in practice.

There are many examples of very large and critical software systems implemented in languages like C, C++, Java, C#, Perl, Python, Ruby, and others. We just don't see anything like this when it comes to Haskell, however. The examples that do exist are quite minor in reality, and this will naturally make some people skeptical about Haskell's practicality.