Earlier quoted context omitted.
i9 macbooks had so poor thermal performance that system was grinding to a halt if you tried to do stuff like run tests on all more than few cores in parallel.
I'd be surprised if you could get genuinely good thermals on an i9 in a laptop. And that's partly on intel - i9s just have bad thermals, especially recently. Besides, if you genuinely need the power to justify using a chip with that kind of TDP, you should be looking into a desktop anyway. It is worth noting that Apple may have been intentionally neglecting thermals pending the transition to ARM - LTT did a few video…
Gaming laptops do try and provide enough power and thermals to run full tilt. For work I chose an Alienware m15 because of this, and I wanted fast over thinnest. The m15's offer an i9 and probably could run one near full thermal load. In my case a desktop wouldn't do since I need to move around (doing IoT stuff, so I goto different parts of the lab). But, I do miss the macbook pro build quality. The first m15 died, and the replacement has a dead pixel.