And here I get to correct you for a change
I hate to have to correct you back
It's actually a very useful method of measuring wind speed.
It is indeed quite useful, even the preferred method, but only in a very limited set of circumstances. It is used mainly in lab and wind tunnel situations where the conditions are very controlled. Its biggest advantage is that it is extremely responsive for detecting small changes and is small enough to not interfere too much with the environment it is measuring.
It is also used in the field for in-flight or on the road aerodynamics. There the air mass is not controlled, but the instantaneous changes are still accurate enough to detect turbulence and boundary layer separation.
It is also the only game in town when it comes to really low speeds. Not because it is particularly good at those speeds, but because everything else really really sucks there.
I still maintain that it is not a good method for doing generic airspeed measurement. But for a school project, where you can show a number changing when you stick a device out the window, or blow on it, it is just perfect. Helping students do their school projects.... that is a different discussion for a different day.
---55p