Depending on the size of the resulting modules, you may run into build-time slowdowns due to the limits this style places on separate compilation. A recent post also suggested some typechecking slowdowns when files contain many modules directly. Whether or not either of these would matter in practice would depend on the specifics of your project, but they’re worth keeping in mind
(I initially misread your post as suggesting the entire project be in a single file, which would make these issues much worse)