(First: let’s not debate the motives — like you I can see reasons for wanting to hide users’ contributions, e.g. someone with an enduring habit of blurry photos, or dropping thousands of ‘unknowns’, or…)
Filtering by “unwanted user” + increasing per_page to 200 + marking everything as ‘reviewed’ certainly does the job with removing existing observations from sight, but… it has to be repeated every now and then, as soon as the “unwanted user” adds new “unwanted observations”. Not very proactive, not very convenient: one has to remember to constantly and correctly add “¬_user_id=Alice,Bob” in the URLs.
A general setting like this would go a long way. For example, it could take the form of an option in one’s profile “Hide these users from Identify and Observations views:”, with a list of unwanted users to hide for some duration (permanently until manually removed, or for n days, or for the lifetime of the cookie - a month?)… without resorting to hard blocking, a function intended to mitigate abuse if I understand correctly.
If there’s interest, and not already in the works, I could prepare a Feature Request to this avail?