This is anecodal, but when I was a product manager at the WMF, I did this sometimes. As is true in any company or project, there will always be tickets that contain valid bugs or requests, but the reward per unit effort makes them not worth fixing. I often tried to close these as declined to reflect that reality, but not infrequently someone outside the team would reopen the ticket. The path of least resistance to stop team workboards being filled with tickets that would never be actioned was to mark them as lowest priority, and then use a filter to remove those tickets from our views of the board.

I don't particularly have a view one way or the other on removal of the "lowest" priority. The workflow I described above wouldn't really change; "low" could just become the new "lowest", but people wouldn't find it demoralising, I suppose?

Dan