Dropping the user_id requirement is something that I would like to do, as it is the best solution. I hadn’t found an efficient way to do this yet but it is the correct solution.
As this will go into JSON API 4, I cannot provide an estimate. As a general rule I only provide estimates for defects, not new features, since it is impossible to estimate how long things take.
I will look into how to eliminate the requirement for a user_id argument and let you know.
with regards