Can anyone tell me why the "yanky hands" - someone pumping their hands & arms up & down their horse's neck when running - is done by so many anymore?  I can't see how that helps a horse go faster/run better.  I feel someone with quiet hands - whether they go up the neck or keep them closer to their body as long as not pulling back - is much less confusing & distracting to the horse, & the "pull/release/pull/release/pull" of the other would be a mess. 

I think it goes through phases but look at the people who are winning, they have quiet hands. Cassie Mowery has about the quietest hands of anyone I have seen but her horses are so broke, they don't need a lot of pulling or anything else. Look her up on YouTube. I have a "new" horse (I raised her). You have to just put your hand on her neck and hang on. It's really nice but is going to take some getting used to. I'm not a jerker but I am used to doing the driving. 

Alot is how one is taught. Being a hunter / jumper person as a kid I was taught quiet hands & thats how I ride a barrel horse. Sherry Cervi has the best hands ever. She was taught that by her parents. I know a girl who has those wild hands. If she leaves a barrel standing, it's a miracal 

Most riders including the professionals will and tell you how to ride the proper way. 

Then go and make a run and every thing gets thrown out the window. 

It drives me nuts (I know, not far to go there! LOL) to see that in a run.  I would post a video of a good example but I don't want to target anyone - so I hope my description was good enough to get the picture.  One in particular has her hands going 90 mph & her butt is all over on top of that horse!  I've seen her run in person & her vids she's like that in all of them.  Sometimes the poor horses she rides make a decent run, in spite of her.  

Truth.  I wish I was a perfect rider but I drop my hand to the inside about half of my runs and my current mare will leave me behind regularly.  Sure glad my horses take care of me and make me look decent in spite of myself.

It is a skill and like anything else it has to be learned...some are quicker at it than others.

I have fairly quiet hands but still concentrate on it and my legs....I tend to nag with my weak leg.

If they are out running everyone else then obviously there is a method to their madness.

I have seen some of the best jockeys and trainers ride both ways according to what gets the job done.

Myself I was taught the political correct way but these days it all falls apart when I am riding and not much is happening at the pay window.  

but the ones I am seeing are NOT winning.  And much of the time, you can see the expression on the horses' faces are like "WHAT?????"

Hence the reason I said "If".  
As a rule I shy away from being critical on how anyone rides. 

And in my OP, I asked why do people use this "style"?  Always good to learn something new if it is a better way.

Why worry about? If that is the worst thing those horses have to put up with, then they are pretty lucky. 

who's worrying?  Trying to find out what the benefit is of it if it is a good thing?

I think they get too excited  or they think its a way to push faster or they may not realize they are doing it or habit they cant break!

On the quiet riders it looks like they may not be doing anything but they can be doing alot.  I had a friend that told me a mutual friend said she wanted to borrow my horse bc I'm doing nothing and my horse looked be soo easy to ride.  I took that as a compliment bc I did put alot of work into her off the pattern.  My friend said she told her that I'm doing more than looks you just cant see it! (She has rode my horses before) That made me laugh and got me to thinking what do I do lol 

And I wonder maybe that style worked on a previous horse but not the one they running and they havent changed for the horse they running. 

That doesnt work for me but I will try something to see if works for me and if dont I try not to do again! lol

We had one lady that screams at her horse every step of the way and loud but she beat us!  so of course I tried it once and I mean just once! lol didnt work for me!

I watched a little girl run a pony for long time and did really well on her! and she rode a couple of big horses after that and did well on them to but she had to really lean forward on them to keep them moving.  Now she struggling bc she had a huge growth sprurt! has legs now lol and leaning forward doesnt work with her 2 new horses now.  but she young and will figure it out bc she got awesome people helping her.  But habits hard to break sometime! But hers started with the pony!

I can only speak for myself on this, but I've found it depends on the horse and their stride. I look like an idiot pumping my arms back and forth on my big 16.3 gelding, and try SO hard not to, but it just happens. I stay quiet on all my others and have never had a problem before I purchased this gelding. 

Everybody just rides different from one another, just think how boring it would be if everybody rode the same way as each other.

I think the best riders are the riders that do what they need to do at the moment it needs to be done...take Lisa for instance at Calgary on Rosa, turned the 2nd with the wrong hand on the reins.  Like she said in the interview it was the wrong hand but sometimes you have to do what you have to do at the moment to get the job done.