I think there’s a huge difference between a swing coach and a golf coach. A golf coach to me would have a more comprehensive scope that includes mechanics, strategy, mental game, stats, etc. I would be very interested in that but the issue is finding someone who would do that. Seems most are geared to different sub-segments.
I also think it really depends on the area you are in and what the supply of golf is, can be difficult to find anything above the golf pro who gives you the plain vanilla.
Personality type also plays a big role. I like to get some pointers but then figure out things on my own. I see that there is probably a market gap for on-line holistic golf teaching where you can mix with library of videos, sending in your swing, live chats, etc. etc.
We all learn differently, Jimi Hendrix figured out the guitar on his own and he was pretty good To some degree we all can benefit from good instruction but I think how much you get out of it will depend on many factors. So like golf there is no easy answer!