Because the language already does everything it needs to do for the space that it's in, which makes it easy to create frameworks that are little more than movin

Because the language already does everything it needs to do for the space that it's in, which makes it easy to create frameworks that are little more than moving things around and/or defining rules for how to structure things. You see this in Javascript and PHP where there are tons of frameworks because the language already has so much built in for the problem space. Other languages that aren't designed to be web native, general purpose languages, tend to rally around frameworks geared towards opening that problem space to the language.