Actually they are related. Why should one party be allowed to decide after the transaction that "well, I think it was a mistake and even though you believed you would get miles I've now decided you wont"? If a near zero $ fare than maybe no argument from me, but look at the examples many of cited in other threads about missing routing rules and other things that in retrospect may have been a mistake but that many purchasers could have bought in good faith. Is AA allowed to after the fact say that you will only get miles for A-B and not A-X-Y-B because they forgot to include restrictions on routing rules?
The fair outcome in this entire area is ultimately about balance, and while your posts all seem to focus on near zero $ fares, that is only a small universe of what I would call "high value" fares, where the cost may actually be "normal" but you get more routing options.
I would argue that if an airline gets to after the fact and unilaterally (without regard to the state of mind of the purchaser) mark fares as non-mileage earning than they are potentially going way, way beyond the doctrine of unilateral mistake (which the DoT has now more or less reinstated). Look at the basic confines of the unilateral mistake doctrine, it doesn't say that the mistaken party gets to void any and all contracts, it in fact makes it clear that the state of mind of the other party is relevant and needs to be examined, so there is an individualized examination that has to take place. A carrier can try to put whatever they want in their CoC, whether it is enforceable and whether it results in the DoT revisiting this issue yet again in a year is another story altogether. And by the way, allowing the carrier to unilaterally change terms but not allowing the passenger to cancel, sure seems perfectly fair to me...