I use it to spec out the PSU by adding up the TDP of CPU, GPU, MB and other components and then adding a percentage. So I expect the numbers to be accurate. That's why I was so surprised when I started seeing PL2 numbers.
They are not innacurate: Intel defines the TDP as the power dissipation of the chassis required to sustain at least the base CPU clock when running a prolonged complex workload on all cores. It’s basically a promise to the system maker, if you can dissipate X watts than the CPU will sustain at least Y ghz. It’s just not that useful to a user. Intel system run hot and noisy not because the Mac chassis is not enough to take care of the TDP (they can dissipate much more heat in fact), but because a) the CPU will often run way above its TDP, hearing the system up and b) even the smallest burst workload will push the CPU frequency to its max, again heating the CPU up. Disk indexing? Heat. Backup? Heat. Running syntactic analysis on a code file? Heat, heat, heat. The system is more often at its peak thermal load than not.
Apple Silicon is very different. You only get to the peak thermal load when you actually run a demanding workload, often one that utilizes multiple clusters (like CPU+GPU) Background things like indexing or backups don’t even show up because the E-cores will take care of them. And even burst workloads require a fraction of energy than with a x86 CPU. That’s why M1 macs are so cool and silent even though the sustained power dissipation is the same as their Intel counterparts. Of course, with M1 sustained dissipation is the peak dissipation. With Intel, peak dissipation can be 100W for a 15W TDP.