...It's too early for your pedanticism.
I mean, if IFC wasn't giving Navi21 enough bandwidth then why is Navi 21 faster than the GA102 in essentially every game at <4K and very close at 4K. And we are talking about games, because these are gaming cards.
I despise crypto currency mining and I can't be bothered to link the myriad posts I made to that nature, but the babble is aimed at gaming workloads, so your main complaint is semantic. -_-"
Navi 21 doesn't have anywhere near as much stress on vram bandwidth as ampere. Even if the hit-rate was as low as 30-40%, that's still a huge chunk of transactions that misses L2 that are still not going to vram, and not using up bandwidth. Unless the workload is using data sizes that consistently exceed 128MB (so not gaming graphics) there isn't a time when Ampere has more effective bandwidth than Navi 21.