IDONTWANT is not the opposite of IWANT
IDONTWANT sounds like the clean negative image of IWANT: one peer asks for a message, another says please do not send it. The row counts even make that story tempting. On July 1 UTC, Xatu's mainnet libp2p sample had 56.2M IWANT rows and 48.8M IDONTWANT rows.
That neat story breaks as soon as you dedupe the message IDs.