Can you imagine anyone taking a private lesson on how to nail the nail with the hammer? Explaining how to hold the hammer and how to try to use the center of the hammerhead to meet with the nail cap would be the extent of it, as far as I see. Now think of someone starting to elaborate on this subject explaining this process in depth. That would be over-teaching, wouldn’t it? The concept of “hammer and nail” is pretty clear and self explanatory, mastery would come with practice and not from theoretical research, nor from better awareness of the “outer form”, such as to what degree you need to bend your elbow, weather you use wrist little more than your shoulder or vise versa and etc. I cannot resist throwing couple more examples of using simple tools: shoveling snow, whacking the fly with a fly swatter, using a spoon or a fork.
Being VERY(!!!) guilty of over teaching as a tennis instructor myself, I totally admit and agree that tennis strokes teaching should be more simple. At the same time anyone who tried to teach the overhead serve with continental grip* would agree that this particular serving concept is very complex, if compared to just a fly swatter action. By the way, topspin ground strokes are pretty complex, too; the serve is the “king of all skills” since, potentially, it is the biggest weapon of the game. Using continental grip and bringing the racket square to the contact with that much speed and therefore force is absolutely disguised and not very obvious at all. There are some coaches that would not even recommend serving with continental grip to the kids under certain age. I am assuming that these coaches believe it it is impossible to explain to the youngsters how ‘the continental grip serve” works.
I do not see, how this motion can come to anyone, only by observing and practicing without being explained in detail at some point and taught as a trick. Majority of players who learned to serve really well had taken serving lessons. The rest settled on what they figured and made it work for them. To be completely honest, there are still plenty of players that took lessons, often many lessons, on serving and still have very little confidence and satisfaction in their serves. That confirms again very important reality that every player is unique and there are no exact same forehand, backhand or serve motions out there, even by the same player (the ball never comes the exact same way).
First thing that is done 99% of the time is the attempt to learn and teach (!!!) the overhead serve by mimicking the “outer form”. When teaching the skills “outer form” ques are being used by EVERYBODY starting from self taught amateur players, tennis parents, and all the way to the teaching pros of all levels. At the same time those ques often do not explain the internal reason for the benefit; it’s just feels good or better when you do this or that, like jumping when serving for example. I guess there are miracles and players can intuitively fall into the rational motion. I am, yet, to see this happen.
Serving motion, as well as ground strokes swings and volley punches, show that the “conceptual” applications of a racket in all these actions are totally disguised and not obvious to an uneducated viewer. There is plenty of grace in all of them when performed certain way, by Roger Federer for example, but that makes those motions even more mysterious. I do not play any musical instruments. The miracle of those wonderful sounds are still fascinating and hidden to me, (with exceptions of the drums, may be), but when musicians play, most people, including me, get caught in a some degree of admiration. The best players to me are like the best dancers and musicians playing impromptu at the highest possible speed rate. That is how I relate to the mastery level of the use of their bodies, minds and tennis racquets by the best players. And that is why tennis still needs to be taught.
There is a big difference between teaching “outer form” that describes where the racquet starts and finishes and teaching the content that explains or helps to understand the production of “tennis music”. Unlike teaching to use the hammer, teaching to play violin will not be limited to explaining the basics only. To become truly good tennis player, you need both approaches: simple and in depth. As a player you need to feel how “racquet plays the ball” early, so you can function and play the game as soon as possible. But then you need to continue to study how you enhance the racquet action by adding actions of your body. For coaches to truly teach that to very different students is an art and it takes a lot of courage and honesty.
*Continental grip is one the ways to hold the tennis racquet. I like to explain this grip to the the players as a grip you would use when you would hold a hardcover book by the spine. Arguably, and I agree with this, continental grip is the grip two-handed backhand players use for their dominant hand all the time, except when hitting topspin forehand. One handed backhand players additionally use different grip for the topspin backhand.