Some of the pgweb folks have discussed doing that before; it's not a bad
idea, and perhaps would cut down on some of the headaches.
That was in fact the original plan, nobody just got around to building it. There was even a db field for it in the early dev snapshots, but it was removed since it was never quite done.
The general idea was to just have a "last confirmed" timestamp field on each entry, and just stop showing any entries that have not been confirmed in <n> days/weeks/months/whatever. We can keep them around some extra time beyond that in case people come back to update them later of course.