The point is that Amazon doesn't have to fill that slot with a c6gd. They can also fill it with a c6g. They just choose not to.
The fact that you have to host a c6gd to get that price instead of a c6g is an inefficiency in the spot market that likely makes Amazon money, but is a little customer-hostile. I think the article is probably wrong that Amazon is foregoing revenue due to this. This is a form of price discrimination and it is likely making Amazon money, but in a scummy way.
Agreed that it's definitely difficult to know the true missed revenue here without internal data, and even then you'd be making some assumptions. I am confident there is some missed revenue here, as amazon routinely has spot capacity constraints under existing prices so could definitely sell some substitute instances without moving the original instance market (even one instance per pool substituted equates to >$1M per year). In either case, a savvy organization can definitely benefit from the price discrepancy even if Amazon couldn't.
I can agree that there is missed revenue - but realistically it wouldale much more sense to sell that capacity via Fargate (which is closer to undifferentiated generic compute and RAM) rather than monkeying with the spot pricing algorithm.
Great point on Fargate, I'd be very curious on whether they select capacity for that from EC2 capcity or if there's a separate physical footprint for it.
The fact that you have to host a c6gd to get that price instead of a c6g is an inefficiency in the spot market that likely makes Amazon money, but is a little customer-hostile. I think the article is probably wrong that Amazon is foregoing revenue due to this. This is a form of price discrimination and it is likely making Amazon money, but in a scummy way.