Regarding slow motion, this can help understand an initial change, but ultimately you need to keep speeding it up, it's easy to move correctly with unlimited time to adjust, which is why it helps to feel a new movement, but why slow motion alone won't transfer to a normal swing without other work.
However, I think the real issue with learning and teaching golf is the obsession with positions, and particularly positions of body parts, over movement and outcomes. When humans learn most motor patterns, they do it through having a goal and adjusting to that goal. No one learnt to walk or run by consciously considering how much ankle, knee and hip flexion they had at certain points during the stride. They set a goal of "I am at point A, I want to get to point B" they then trialled and errored until this happened. Golf needs to be the same, we know we need a certain swing path, angle of attack and face angle at impact (plus a bit of swing speed). If we have a tool like a trackman to give us feedback on this, we can subconsciously adapt and try new things until we start producing the results we want. For the most part, if you generate good impact numbers, the swing itself won't look bad with regard to fundamentals. In order to do this, we need to understand what needs to be happening at impact and have feedback on this, the ball although eventually the ultimate indicator because it's what matters when we play, is not the best indicator for a non-elite player, as a good or bad result can occur due to a matter of millimetres, regardless of overall motion. Take a shank, for example, a heel hitter could barely miss the hosel and the result would be much better than an impact that was 1mm more towards the heel, yet in reality, both swing motions are just as faulty.
Final point, for some reason hand-eye coordination gets massively overlooked in golf. I assume this is due to the static ball and people thinking if you swing perfectly robotically you will return to it. In reality, during a round, apart from off the tee, you have to deal with so many different lies, that hand-eye coordination is essential to make the minor adjustments. When practising, as well as simulating course conditions, you should also train just stepping up to a ball and hitting it, or have a friend roll it to you and hit it. This has the added bonus of making it less of a static motion, the swing will become more natural.
I think sports science is slowly catching up in golf and maybe we will see more non-traditional learning ideas becoming more mainstream.
