If abuse is an issue, why not hash the IP with a nonce?
If you don't know the nonce, you can't match against other users-- so not useful for abuse.
But I'm skeptical re: abuse uses. For commenters, sure-- you may need to store IPs to combat abuse. But for readers? At most you would need sampled data or in-memory counters (e.g. to catch high volume bots).
Unfortunately, there really isn't any penalty for failing to minimize private data collection.