Lets go back to Ancient Greece - I mean, way back. Xenophon was the first man who came out with a horse training book titled "The Art Of Horsemanship, A Training Guide For War Horses" and it rippled down from there. Not saying he was the first to ride.
To the Romans, to the Austrians, to the Millitary, to what we see today. Of course there are others that fill in the gaps between those I've posted....but that's all I can think of right now.
We can watch an Olympic Dressage Competator ride a test, and we can see bits and pieces of the heratige of riding in their style and way of going. We can look at some Hunter/Jumpers and Eventers and we can see remnants of the Millitary style.....
The point is, is that riding has evolved. Education has evolved from greats of the past - and what we see today at top levels is where it is for a reason. Many of those "Greats" had coaches, who had coaches - who molded them and formed them into what they became, to beable to be that much of an asset in the riding world.
Big names like George Morris, Jim Wofford, David O'Connor, Beezie Madden, Eric Lamaze, Rodrigo Pessoa and the list goes on. They all had coaches, and now are coaches, who still move forward in their education and experience. Who's students will become coaches and make it in the sport.
Of course there has to be natural ability and talent and the gumption to get up and learn and grow themselves, but you can't make it anywhere without guidance and assistance from someone who is already there. Doesn't have to be a Pro, but should be higher than you in levels.