I've never heard of this before - I think you need a second opinion, preferably from a cat's only vet.

Generally the redness at the gumline indicates some gingivitis is present and they should have their teeth CLEANED by the vet, not PULLED. Also the vet should then give you instructions on how to clean the teeth yourself and you can try to train them into this habit at home. There are also various drops and such out now to use to neutralize bacteria so vet cleanings aren't required so often.

I recommend you pick up a copy of 'Think Like a Cat' - these basic cat health issues are good to be informed about before getting into a situation such as what has occurred here. It's hard to determine if a vet is offering competent advice if you don't know the basics yourself.

If a cat-vet tells you it's standard to pull teeth out as treatment for mild gingivitis I definitely want to hear about it. Frankly if the situation is as you described I'd consider filing a complaint with the vet licensing board over the advice you were given. Anyway, first order of business is a second opinion.