First, you're moving goalposts (the initial question was about how or why noncompetes are anti-worker, anti-competitive, and/or anti-innovative), and doing so without acknowledging the point. Chalk it up to my own history of arguing on the intartubes, but I find that tedious and generally a Bad Sign of things to come.

Secondly: my second point answers my first.

Markets don't manifest in individual transactions, they manifest as the emergent behaviour of multiple transactions. As others have noted, setting bounds to what can be traded away has proven necessary, empirically, to avoid winding up in a highly non-optimal equilibrium point.

If you're interested in ethical ramifications, I recommend two excellent works on the topic: A Theory of Moral Sentiments and An Inquiry into the Nature and Causes of the Wealth of Nations.

Even that treatment is unsatisfactory as it neglects considerations of short-term vs. long-term trade-offs.

Your example is contrived in that it essentially poses a Sophie's Choice: give up condition of long-term viability A or because of my superior position in establishing and enforcing terms, give up condition of long-term viability B.

The optimum condition would be for no artificial constraint on A or B imposed by the employer.