Boraxo, your post is way too logical and makes too much sense for a discussion of airline policies.
Why hasn't an airline tried
WonderDude's idea? Maybe they fear that FF'ers would find a way to "game" any system they set up. Even one as simple as "Find a fare, book it, inform us that you won't actually fly, and we'll cancel the ticket and award the appropriate EQM's" - they (likely rightfully) fear we'd find a loophole somewhere and share it with the world - sort of like we do MR's today on this board.
But...with MR's today, you kinda have to be in the right place at the right time and willing to actually fly, so even the sweetest MR doesn't attract more than a few people. I can only imagine how many of us would strike the moment someone posts a $175 all in transcon with a circuitous routing if we didn't really need to fly it.
More likely, I can see airlines saying "Buy EQM's for X cents apiece." (Of course, they'd be pricey.) Since they all sell RDM's, and some allow you various ways to prepay or pay to renew elite levels, it might be coming. UA is dipping their toe in the water here with "Choices". One can swap 10 RDM's for 1 EQM. It's unlikely that I would really do it - if I'm sitting at 97k on Dec 31...ask me then. But perhaps it's a harbinger of things to come.