Do you have any source whatsoever for this? Companies enforce non-competes all the time. Wall Street Journal thinks it is rising 60% over the last decade (2013)[0]. I think your experience of what you "have seen" is wildly out of touch with reality.
I tried to find a source supporting your position, that companies don't enforce non-competes, but couldn't. The best I found was this[1] article about one lawyer willing to take on NCA cases for employees on extreme-contingency arrangements, since he apparently practices in a state where fee agreements must be reciprocal (i.e., if there is a fee agreement in your NCA, you get your fees paid if you win). If you live in such a state and can get that man to represent you, great. Otherwise, as he describes:
>There have been several cases where we have invested $100,000 worth of attorney time and $10,000+ of hard, out-of-pocket costs to defend a poor or working class person against a bogus non-compete agreement. And there have been a couple cases where it’s gone far past that: $200,000+ in attorney time, $20,000+ worth of case expenses. I’m sorry, but no other lawyer in America does that. I’m the only one.
>In many of these cases, you will need to execute perfectly or you will lose. You have to make 100 perfect moves and the other side only has to get 1 thing right. It’s absurd. It’s messed up. But that’s how it is.
Now, in reply to you saying: "It’s a stupid posturing game that rarely works."
This individual does agree that in many cases the companies are posturing and will lose. But unless you can afford the $XX,XXX-$XXX,XXX to pay a lawyer to get there (or find a unicorn, like him, who will work on contingency), you lose by default. Whether you think it's a "stupid" move to posture or not, the companies do it, routinely, and at an increasing pace.
[0]https://www.wsj.com/articles/litigation-over-noncompete-clau...
[1]https://www.pollardllc.com/poor-people-non-compete-cases/