I saw some projects in which my instinct was "too many repos" (e.g. https://github.com/ActivityWatch/activitywatch), exactly for the reasons you mentioned.

However, in my case - as the project gets bigger, I appreciate it more. In the first place, it makes code reusable, and forces to encapsulated functionalities as much as possible. (Yes, having non-encapsulated code would be a nightmare).

To get to the extreme, in the Node ecosystem code is pretty much structured as many, many small packages. (Bear in mind, that turning something into a package is a much stricter requirement that making it effectively a subfolder.)