i had the same reaction (lua resembling python but with a focus on small footprint and a much smaller standard library.)

having "batteries included"/mature web frameworks often trumps the innate benefits of the language, i.e. other people who have spent thousands of hours on mostly boring glue -- ORMs, unicode support, templating engines, caching, getting around browser quirks -- to enable you to focus on your app.

furthermore, you're generally going to be bounded by IO/the database or RAM or some other factor in which case the speed of the language is mostly irrelevant.

it's certainly possible to do web development in any language, but why bother swimming upstream when python/php/ruby do a lot of the hard work for you? it's hard enough just to write your application without having to write the infrastructure beneath it too.