Apple has historically seemingly been allergic to good thermal design. I would not be surprised in the least if they were leaving a lot of performance on the table because they'd rather do that than design proper cooling, despite how silly that sounds.

(Although with the m1 line it actually makes a bit of sense for once - it is useful to the end user to set things up so that fans /never spin up/ and the laptop never gets hot to the touch. Whereas with their previous intel models they had terible cooling and still had all of those problems, while not actually achieving a size win over a lot of competitors "thin and light" models that actually had competent thermal design)