The explanation for the foregoing is that agents watching a listing — or their clients — will note that a listed home has suddenly disappeared, and will contact the listing agent to see what’s going on.
In today’s market, homes that cancel or expire invariably pop up the next day or two, at a new price and/or with an extended listing term.
P.S.: MLS has a feature that lets prospective Buyers “watch” a listing for any changes in status. Listing agents can see how many times Buyers have saved their listing — but not the identity of the Buyers.