All sports are pointless if looked at from the perspective of usefulness
Apart from swimming!
No, swimming is equally as useful as lots of other sports, as many have said above doggy paddle works fine for most swimming survival situations (anything where it doesn't you should have a life-jacket some other sort of flotation device anyway) The strokes are there because they are faster / more efficient etc.
You need to develop strength to get you our of all sorts of situations - pulling yourself out of the water you've fallen in for example - strength sports do that.
You need to develop the balance and co-ordination to not fall in the water in the first place, Agility/Balance/Coordination sports will do that.
Gymnastics is great for ABC and strength, but it's terrible for safety, if you have to jump from too high to be safe, you don't want to land with your feet together and your arms stretched out with a big fixed smile on your face. You want to roll out to make the landing safer, are you doing gymnastics 'cos it's a fun sport, or for safety when you need it?
Sports adjust the demands to make it fun, and provide rules that can demonstrate the skill - butterfly is fun to do, dolphin kick I think is useful in very shallow water, but mostly it's 'cos that's the sport.
If you buy lessons from the Sport association, don't be surprised that they teach the sport, obviously that is what they want to do - build their sport.