If you choose not to apply a protectant, that's fine. Just make sure your reasoning is based in the real world.
Of course protectors work. How well depends on the product, how it's used and what it will be applied to... there are variable like everything in life.
I've cleaned a horrible commercial wool that required pre-shampoo treatment before every extraction cleaning - until I treated it with a fluorochemical protectant. From then on all it needed was wand cleaning. I've done a dozen tests of protectant application in various commercial accounts and found the protectant always makes a difference. Treat the worst ones even if they won't pay for it, simply because it reduces the difficulty of cleaning so much that it pays for itself in reduced cleaning time.
Health effects? Possibly, but your chip bag and burger wrapper don't leak grease because they're coated with a fluorochemical. If you're worried about your health, wear PPE. If you're worried about your customer, don't be; they, and you, are ingesting far more Teflon from the cereal box liner than they'd ever get from the carpet.
PS: Randy, Silicones are far cheaper to produce than fluorochemicals, so who's getting ripped off by the really expensive product manufacturer?