I shouldn't have brought up logic and statically-typed programming as specific examples; my point was more that it's misguided to consider the "power continuum" as one-dimensional, where languages lower on the continuum are "dumb" and languages higher on the continuum are "weird". As you said, a language with good types is not necessarily more or less powerful than a highly dynamic language.
I'm sure that they had a good understanding of their customers, but the language had to have made a difference as well. These days, we're writing web apps in languages like JavaScript and Ruby, not C++, so the difference would be a lot less significant.
The idea that LISP was a secret sauce for viaweb does not hold up under scrutiny.
If you have access to lexisnexis to lookup news articles from the era, it’s easy to see that.
I don't think that the fundamental flaw with that essay is the arrogance so much as the assumption that "language power" lies on a continuum in the first place.