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.
This particular suggestion breaks down fast when you have multiple employees that need to collaborate. If you have a million dollar strategy, you can pay half a million to an employee as a retention bonus. But you can't pay half a million each to 8 employees.