That may (or may not) be true. But in my experience, at least some percentage of people bound by non-competes elect to just be on the beach rather than going the legal route. Some companies have a reputation for consistently litigating these.

In addition, even if the employee/ex-employee is willing to risk it, lots of potential new employers aren't. I worked for a small firm for a number of years and we wouldn't even entertain having discussions with someone if they were bound by any remotely relevant non-compete.