You don’t exactly need to ban them, but the employees should be compensated during the non-compete period and limit the lenght of the non-compete contract. In Denmark my employeer can’t make non-compete contract for more that 12 month, during which I’m entitled to 60% of my salery. It’s also only valid within the same field. That is: You can’t jump from Microsoft, developing Windows, to Apple and work on macOS, but y…
This sounds good in theory, and I was once presented with a job opportunity with something similar to this. Except much of the compensation was not in salary. So while salary goes down 60%, total comp goes down way more -- all the non-salary components goes to zero.
But you could fix this with craftier legislation instead of banning non-competes, e.g. maybe you have to pay the persons last years total compensation instead of just their salary