I'm wondering if it's because they're hitting the limits of the architecture, and it sounds way better to compare M4 vs M2 as opposed to vs M3, which they'd have to do if it launched in a Macbook Pro.
Eh, they compared the M3 to the M1 when they launched it. People grumbled and then went on with their lives. I don't think they'd use that as a reason for making actual product decisions.
