Pretty much all the listed cons are just about having to migrate large amounts of code (regardless of what sort of migration it is). Didn't really seem to have anything to do with monorepos at all, really. Which is not to say there aren't big cons, but they're not discussed here. Neither are the pros, really
I did not see any point to listing out the cons as others have already done it a bunch of times. I was trying to focus on what moving to a monorepo solved for us (which was optics and poor ux).