I think people do often make assumptions of how good a player is by handicap and many times it does hold to be true. However their scores don't necessarily indicate what type of player they really are. I recently played in a tournament with a guy who was listed as a 15 handicap but didn't hit the ball very far at all on a 6600 yard course. He was just out there having fun and said he would go nuts if he shot 85. He would hit his driver maybe 200-210, but would always have to hit a hybrid onto every green, very rarely hitting irons. He even had to hit driver on one par 3 and didn't make it there. He did end up shooting 85 and I shot 84 while hitting almost every fairway and a few of the greens in regulation. People were surprised that we shot so similar just because perceptions about distance, accuracy, or technique. So people can shoot pretty consistently if they can figure out what to do (i guess it helped that he was regularly taking lessons and knew a bit about his swing).
But I don't think it is out of the question for a 15 or so handicap to have a lot of knowledge about a golf swing or equipment for their game. I'd like to think i know about equipment and technique just as much as a single handicap just from experience, reading, practice, and gaining knowledge from everyone I've golfed with. I believe that there are golfers with single digits and golfers who are around 11 or 12 that are around the same skill level, with the single digits having a bit more experience or composure. I don't think there is as great gap between skill level as perceived.