Dispute resolution is not where the 2-3% go (as evidenced by disputes also existing on US debit cards, where it's 0.05%, and EU credit and debit cards, where it's 0.3% and 0.2% respectively).

Some of it is spent by the issuer on fraud expenses that they are assigned liability for, but given the same reasoning as above, if that was more than 0.05%, there wouldn't be any profitable debit issuers left in the US (and similarly for the EU, although the regulator is changing the fraud calculus there significantly by enforcing strong cardholder authentication, so it's not an apples to apples comparison).

In other words, if there was political will to get rid of credit card points in the US, we could have all of this for much cheaper. (We might need to look into scheme fees too while we're at it, e.g. by finding a market solution that creates actual competition there.)