The point of a monorepo is that all the dependencies for a suite of related products are all in a single repo, not that everything your company produces is in a single repo.
Most people use the "suite of related products" definition of monorepo, but some companies like Google and Meta have a single company-wide repository. It's unfortunate that the two distinct strategies have the same name.
Just a note OMR (the office monorepo) is a different (and actually much larger) monorepo than 1JS (which is big on its own)
To be fair I suspect a lot of the bloat in both originates from the amount of home grown tooling.