The two main issues I have with them are that firms tend to give them to just about everybody (instead of just to folks working very directly with real IP), and they only pay base salary, not something closer to actual total compensation (often multiples of the base pay).
Having said that, the quant firm is relatively unimportant and not a good reason to prevent a total noncompete law. It's probably better to just ban them then try and make allowances that aren't full of loopholes.
It sounds so profoundly anti-capitalist - if the knowledge of certain strategy is so important, the employee should be retained by paying them more and giving them better perks instead of enforced labor contract.
But I think it is slightly silly reading your statements knowing that the individuals in that hyper specific industry are top earners already and educated to know what they are signing up for.