> There just aren't good arguments for noncompetes.
I think the standard argument isn't trade secrets. The standard argument is that you want to incentivize employers to train employees.
If I, as an employer, train you for 6 months, then you leave at month 7 for a higher salary (which you can demand cause you have more training/experience), I lose out. So I have no incentive to train you. So training or hiring of people without experience never takes place (or does so at a lower rate).
If you are someone without experience, and there was a way for you to credibly commit to not moving to a new job (e.g. by signing a non-compete), then you might want to make that bargain - it's worth it for you to sign away some freedom in order to get some advantage (which is kind of the basis for all contracts).
That's the theory, anyway. I have no idea how much it holds up in the real world.
> The tech industry in California does just fine without noncompetes.
Obviously, the counterargument is that it could be doing even better, we just don't know it.
Note that if the standard argument is correct, then there's a chance that the biggest group of people hurt by lack of noncompetes are people without experience. You might not necessarily be feeling their pain, depending on your social circle (e.g. if you're a working developer in an SV company, you're surrounded by the people who did make it, not by the possibly numerous people who faced closed doors because of this).