While things like git submodules have problems, are they not sort of the best of both worlds camp?

I never quite got the arguments/grumblings about this stuff but perhaps I do not understand what friction people are hitting up agains. It feels to me the problems of multiple repositories is the same problem of having to manage versions of dependencies like in pip or something that you do not even own.

Perhaps people are using tools that mean they are not able to search/click through their multi repo setup even though the code connects?