Earlier quoted context omitted.
Sure, that's the title, but at least in this PR they immediately show a graph with a comparison to both. Presumably it makes more marketing sense to compare to the M1 family up front because most people that bought an M2 last year are probably not going to be upgrading to M3. They are speaking to the people most likely to upgrade.
fwiw, i cant remember the last time i saw a company go back more than a generation in their own comparison. Apple is saying here as much as they're not saying here. M2->M3 may not be a compelling upgrade story.
Apple likes doing that quite frequently while dumping their "up to X% better" stats on you for minutes.