Think about it...
PM and HRM measure different things...
if, the plan is to use them as tools to improve 'performance', then you'll really want to use both.
PM helps measure how much WORK' the engine does. doesn't tell you thing one about how the engine is actually doin.
HRM indirectly (the best indirect method at this point in time...) measures how hard the effort is to do that WORK... so it indicates how well the engine is working.
you need both, in comparison
to
see how efficiently the engine is getting the job done. HR compared to Power. There certainly can be a lot more used to tuning the package, but this is the cornerstone.
a rider could be grinding out 300 watts and be ready to detonate
OR
could be puttin out 300 watts and just be cranking strongly along...
Power alone tells you not too much, HR alone only gives an indication how hard the engine is working.
Empircally, you can get the same info in a group when you look over and see the rider next to you chattin away while you're chuggin like a steam engine...
no numbers, but the story is the same
from Wikipedia: "In physics, power is the rate at which work is performed or energy is converted"
it says nothing about the engine involved, or its condition.
as to being totally wired or 'Mr/Ms Natural'
there's a whole universe between the rider who doesn;t care how fast or how far they ride and those who need all the numbers, all the time.
There is no 'correct' - just pick your place on that continuum.