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.
Now they don't have 6-24m non-competes anymore, but 6-24m notice periods. You're paid full salary (incl bonus) but you don't work ("gardening leave") and obviously can't work for a competitor (because you can have a non-compete while you're employed).
Like, why would you quite and semi-retire for 1-2 years when you can keep working for like 5 years and actually retire?
(I'm just LARPing, I have been out of the industry for a few years by now...)