[woolvalley]

Engineering resources are not unlimited, so naturally new bugs and features will be updated only on master vs. 2 or 5 major semver branches, because 2-5 module Bs haven't bothered updating yet. If you maintain 5 separate branches, then you're spending that much more engineering resources for little benefit, because you don't have external customers. So the modules that haven't migrated yet decay under a state of deferred maintenance, which is a form of technical debt.

To avoid that, you do 10 migration commits so everyone is on the latest version. If you're going to do that as standard operating procedure anyway might as well make it far easier and have a monorepo.