Vapor chamber only helps with bursts of usage. It’s just that the heat gets transferred faster. Transferred where is the correct question to ask. To the aluminium body is the answer. Now, how much time it takes to heat that body completely (ie: to reach equilibrium with the environment) and once in equilibrium, how much joules (or watts) can the body dissipate into the environment without burning the person’s lap is the point they are optimizing for here.

If you have fans, then the heat transfer is solved, hence no vapor chamber needed, just a large copper plate to be that buffer and then wind takes heat away.

So, no magic here. Energy in must be equal to energy out.