It's not stupid, bu the answer is, to integrate. Yes it doesn't build
really, but if you have 10 people working on a project it's useful to
make sure it's all still working together, tests run properly etc.

With the .net developers where I work it's easy to see that, even if
it wasn't a compiled language, they'd need the CI to keep things
running smoothly.

Admittedly when it's one developer, or developers working on
distinctly separate modules it's not as important.

--Kyle