I don't mean multiple PRs for the same repo, I mean multiple PRs across multiple repos.

Well, if you practice trunk based development, (which at most, is short lived branches that aren't really suppose to last beyond 72 hours for development purposes), its not always best practice:

https://trunkbaseddevelopment.com/

The heart of this being this point: sometimes the workflow of the team demands different ways of thinking about it, and its nice to have that flexibility.

Edit: worth noting also, this does something for those of us using this methodology (I am a big promoter of trunk based development with ruthless purging of short lived feature branches)

Opening WIP PR allows everyone to see several things:

1. what issue is being worked on 2. that it is claimed by someone 3. When that issue was started to being worked on 4. The intentions in solving the issue (if done right)

Those are real wins.

I wonder if the hub client will get a open draft PR option soon.