OK, the BGA trains pilots to whatever standard (up to GPL) they desire, and most clubs also do a lot of air experience flying. What ATC does seems to have changed over time, but it seems most ATC cadets if they are lucky get as far as one solo flight, and a select few can continue.
Most pilots regard gliding as a relaxation and a hobby, not a sport. Sailing clubs are quite different - if you sail on a small inland puddle the only way to make it endlessly entertaining is to race. But the sailing clubs I belonged to didn't develop people with big heads, though it was very hard to shrink them on people who turned up like that. Ditto photography clubs.
You seem to have had some unfortunate experiences with the BGA clubs you belonged to, and any instructor who shouts (other than 'I have' or 'stop') needs retraining. No-one learns (or learns well) when shouted at and adult learners are more than capable of sticking up two fingers and walking. In my view the macho club needed the CFI in partnership with the Board to change the culture. However nearly everyone at most BGA clubs is unpaid, so it can be hard to make significant changes.
Not sure though how the competitive element caused friction amongst the instructors but there again I didn't belong to that club at that time.
But would the ATC have 'dealt with it in short time'? It might depend on which ATC unit you are talking about. Just as each BGA club has it's own subculture (some of them highly undesirable), and each sailing club & photography club does (ditto & ditto), I would be amazed if each ATC unit was an exact clone of all the others.