Those MacBooks were designed when Intel was promising new, more efficient chips and they didn’t materialize. Apple was forced to use the older and hotter chips. It was not a good combination.

Another factor might be that Intel MacBook Pros got thinner and thinner. The M1 MBP was quite a bit thicker than its Intel predecessors, and I think the form factor has remained the same since then.

Yes, but I had about every generation of intel MPB - it never was as good at it as M1 MBP.

The 2012-2015 MBPs were slimmer than the previous unibodies but a lot of that was due to dropping the optical and spinning hard drives. The thermals were not a particular problem. Where that did become a problem was with the 2016 redesign that introduces the wedge-shaped case. The design of that would have been locked in 2-3 years earlier. From what I have read, when the case designs were being worked on Intel was promising Apple that their next generation of chips would be on a smaller processor node and would run cooler so that defined the thermal envelope of the new MBPs. Unfortunately, as we all saw, Intel’s production stalled for 5-6 years and the only chips they could produce were power hungry and hot. That caused problems for those thinner MBPs.

Apple seems to have taken that to heart when they designed the cases for the Apple Silicon MBPs and those have excellent cooling (and more ports).

> My M1 Max can consume (and therefore dissipate) more power than my Intel MBP did, but the M1 thermal solution handles it quietly.

You have to really, REALLY put in effort to make it operate at rated power. My M2 MBA idles at around 5 watts, my work 2019 16-inch i9 is around 30 watts in idle.