Not a real genuine fan of "you don't really know what you're missing, so how could you be missing anything" type reasoning.
There's at least empirical evidence at this point for consumer-facing products that there are visible differences in native versus reprojected methods for reaching high resolution graphics.
It's externally tangible, so a person can in some way argue they are affected enough that the lack thereof is a loss to them. That would generally be needed to progress as far as the lawsuit against Sony over Killzone Shadow Fall, and that wasn't significant enough to carry the case very far.
If they first give the impression that your purchased product is more advanced with a bunch of smart, evolved features which would improve performance in one way or another (be it absolute performance, lower power consumption, whatever), but then never actually deliver on that, then they've sold something under false pretenses. This isn't allowed in other markets, so why should it be OK in computing?
Some kind of negative impact, no matter how small, is generally needed for some kind of court action.
The question of "can you know it's there if you aren't missing it" would figure into that.
The idea of a case is to provide some sort of remedy, the scope of which is in part determined by what kind of injury or loss was incurred.
If the answer is that what was lost is something a consumer cannot detect or interact with, the court's remedy would be equally undetectable--which would likely make a court decide it's a waste of time to look at it further.
I don't recall that either, but I do remember Intel announcing there was a bug in transactional memory handling in Haswell/Broadwell chips. They disabled the feature in all sold processors in a firmware update, including those that would have been bought with that usage in mind. I don't remember reading about them giving any refunds, product exchanges or getting sued over it though. Unsure if they respun the chip with a fixed implementation, or if they simply waited for skylake to reintroduce the feature anew.
I believe some server variants of were able to have a fixed spin.
This is a case where a consumer cannot use the instruction personally, and cannot discern if an instruction is running. Like a culling shader, a transactional memory operation's end results are indistinguishable. Rather, there's the possibility of better or worse performance, as determined by someone other than the consumer.
Perhaps a developer or vendor, say of server software that would explicitly be investing in using the instruction, would be in a position to argue for an actual loss. Intel was either lucky that validation took longer, or delayed the products where the buyers could know the difference. The back and forth with those parties are unlikely to be as public.
