As far as earning in the event of IROPs, it's possible to earn in limited circumstances. Typically it's only possible if you're rebooked to another (non-JV or non-alliance) airline. For instance, your DL flight is cancelled and you get them to rebook you on AA (on a revenue ticket). Decent chance you'd be able to retroactively claim mileage credit for the AA flight (with AAdvantage or another OW FFP, not DL obviously).
This still wouldn't garner any MQM or SkyMiles of course. But if you want to believe that you can earn SkyMiles on DL award flights, go right ahead.