Good question! One generalization of Philip’s excellent point is to Anti-Flake Strategies. In particular, a variant of Philip’s advice: only ever add finite flat spots to Beeminder goals rather than perma-flattening or archiving (unless you’re certain that you’re done with a goal for good).
Another thing this reminds me of is The Great Auto-Ratchet Flippening, which we have obviously not been making fast progress on but which I believe is the eventual future.
Same! Speaking of which, this nice and timely reply to your question is brought to you by my own “post more to the forum” RSSminder goal, bmndr.co/d/forum. 