Let me try to take a step back to the questions before it got muddy.
why a heavy emphasis on knowing what your wind is from the shooting position?
Above is our home range. It rises out of the valley below and crates all kinds of wind eddies and directional switches. Afternoon winds well above 20+ are not uncommon, nor are wind flags flying in opposing directions. Sometimes we are shooting in a wind shadow, others at the top of the ridge where a venturi effect is making the wind speed increase. Point being, I understand your concern about the FFP's wind value being different than the flight path. With that, is it all possible to take it for face value that I understand your premise?
If we agree, let's take one more step and realize that a square range used in F-class, bench-rest, or other traditional NRA sports are not the same as open-country or ranges often used for what a shooter in this forum might be shooting and competing. Most of the square ranges you'll encounter are relatively flat, not across canyons where mirage may not be present. Square ranges often use huge paper targets that suck up the first round lousy shot. Then continue to use sighters, wind flags, and targets with concentric rings. With the
traditional square range sports like above, they're usually working with one target distance
trying to read mirage, indicating the difference in wind values, not the wind itself. People coming from square range sports or with their base only from being around these types of shooters do not understand the value of breaking wind into an MPH value from shot to shot at various distances. More often than not, they will not even use or believe in solvers. Most of the people on the Hide are place a very high value on first-round impacts, key form PRS, NRL, Field Matches to Long Range Hunting. Hopefully, you can acknowledge there are different needs once away from the typical bench crowd.
I will use myself as an example and not have the hubris to claim I speak for everyone or anyone on the site. While I like to think that years on a foredeck, sponsored as a windsurfer and decades of long-range shooting, I am reasonably good at judging wind, it is a localized skill-set that is highly perishable. When I am spun up and shooting several times a week, I see distance and wind one way, but when I travel to a new spot, I am not nearly as accurate. Same if I have taken time away from shooting.
In a nutshell, what the wind meter does is give me a scientific data point to calibrate the overall wind read I am going to run.
The reason I use a windmeter:
A) To keep my brain calibrated to my eyes.
1. While spun up and at my home range, I generally do not use the wind meter, but I still will from time to time to stay calibrated the best I can.
2. Whenever I am at a new location where the visual clues are different, I'll use a wind meter.
3. Whenever I have had some time away from the range, I'll use a wind meter.
B) Practical reasons to use the windmeter.
1. When the mirage is funky and makes no sense.
2. When there is no Mirage.
3. When it is blowing extremely hard.
4. When it is exceptionally gusty and or switchy
I use the data I gather with the wind meter to blend with the information my eyes, face, and brain are compiling to make my call. Then merge the data with what the bullet did.
Value to a newer shooter.
1. See everything above
2. How else are you going to learn what a 5mph vs a 14mph or a 28mph wind feels and looks?
Wouldn't it be better to get good at reading mirage between yourself and the target?
See above.
Restated, mirage is not always present. If it is present, mirage is often not readable to a reliable MPH once the wind direction or speed reaches certain directions and velocities.
Hope this helps.. welcome to the Hide...