Ha! Yeah, true. I can get behind what you’re talking about, but I’ll throw a wrench in and say that I tried this same scaling experiment with a piece of 480×360 archival. I put it in a 1080p sequence and scaled it to 400%, then put it in a UHD sequence and scaled it to 800%. The footage didn’t hold up well, but was nonetheless identical in project and in export even though one was scaled 400% more!
I think this has to do with the relationship between 1080p and UHD being 2x scale and how you view the footage, but it has definitely made me rethink my understanding of resolution and scale.