It depends what you mean by separately. Big organisations can have dozens of teams implementing unrelated functionality with asymmetrical overlaps for conflicts. I've never found a situation where rebase was appropriate for this kind of setup.
If the functionality is unrelated, I'm not sure why rebase would be inappropriate. It just wouldn't matter much other than keeping history clean (and rebase would make for cleaner history than merges).
What is the benefit of this to isolated teams? Rebasing a shared main that is under a constant stream of PRs is tedious and time consuming. What is the justification of this in terms of time spent for a company paying for that time? How is that time recouped via the availability of a linear history?
