I think a lot of the SB crowd (especially the people that call themselves 'tec' divers) like to think of themselves as better or have special knowlege because they can do a basic skill.
Core skills: buoyancy, trim and finning. The first two are straightforward, hover at a depth and in flat trim (the most efficient for finning).
However, finning takes time to master. Scissor kick (aka Flutter kick to some) is THE recreational finning technique found all over the world. It is pretty easy to do and is fairly efficient.
But…. It directs a wake upwards and downwards which will disturb anything within a couple of metres (a few feet) that is below or above the diver. Silt, reef dwellers, corals, sand, etc., are all affected especially if close in. Scissor kick cannot turn you around within your own length, nor can it back you out of a hole or away from a delicate coral/bitey animal.
This is where ADVANCED finning techniques are used. Frog kick and (bent knee) flutter kick direct the wash behind you. Helicopter turns for rotating around your centre point. Backfinning to reverse.
Those are not taught in a basic Open Water or Advanced(!) Open Water class. GUE Fundamentals teach this. Technical instructors may teach this. Most AOW instructors won’t teach this as they are recreational instructors who’ve normally not experienced the ADVANCED finning techniques.
If you,
@berndo, have learned those skills then good on you as you are an ADVANCED diver. The vast majority of divers are holiday divers diving a few times per year who’ve "dun my PADDY" and learned sufficient basic skills in order to follow the leader around the benign dive site in buddy pairs.