ideally yes. However, such a monorepo can become increasingly complex as the software being maintained becomes larger and larger (and/or more and more people work on it).
You end up with massive changes - which might eventually become something that a single person cannot realistically contain within their brain. Not to mention clashes - you will have people making contradictory/conflicting changes, and there will have to be some sort of resolution mechanism outside (or the "default" one, which is first come first served).
Of course, you could "manage" this complexity by attributing api boundary/layers, and these api changes are deemed to be important to not change too often. But that simply means you're a monorepo only in name - not too different from having different repos with versioned artefacts with a defined api boundary.