I wonder how much that has to do with Intel being a node size ahead of the pack. That said, i know they have been trying to get away from the notion of TDP in recent years because they design their CPUs around the concept of "race to idle". In other words that they try to save power by getting things done ASAP and then put the CPU to sleep until there is input from the user or similar.

This isn't really meant to be a comment about Intel vs arm vendors, but features of x86 that make it harder to implement