Practice works after you get "form" down. This is just like for any exercise - be it pure physical, mental, or one like this (which is physical but not in the same vein as a sports exercise)
Now many people can indeed get the form by observing and practicing as you suggest, but IMO the success of that depends much on the nature of the exercise i.e. how simple it is, or how "visible" the form is. For example, if you are watching some trainer doing a push-up or some similar simple physical exercise, and you are doing it along for the first time, your form may be off - but as you watch and train for a few days, you will get it. There is not a lot of magic to a push-up. Now, take swimming. For efficient swimming (where you can do many many laps on a pool as opposed struggle and lose breath after 1-2!), you absolutely have to get form down, which includes coordination. For swimming, this is way more complex than for a push-up. People do get training and direction on form and work on it, and it does take time (since there are a few factors which aren't that obvious or easily visible compared to a push-up).
So, I wonder if this particular case is more complicated, and less tangible/visible. After all you are to produce most motion on your throat, something you don't consciously do, and your mouth and jaw can help, or can greatly distort. So I think there are some subtleties involved in technique here. And, while many do get it, laying down techniques may help faster success for more people. For example, in western music, they have suggestions like relax your throat, chin up etc. etc. Are there any similar ones for our music particularly w.r.t rolling your throat?
I also am wondering if "practice until you get it" offers enough direction. Also "either you get it or dont" (which lot of us, including myself feel
), is bogus. Eventually it is physical. The timbre of your voice you may not be able to change much and may not be instantly appealing to all, but the form and technique, I think most of us should be able to get and execute - with enough training after understanding the techniques.
Arun