For me I am not interested in SFF but more space efficiency. If someone came up to me and showed me a quad SLI 22 core x99 setup with 10tb of ssd and another 20tb in hard drives, and it stays under 60C no matter what (OK doesn't need to do all of this but you get the point) but is 60L, that's just as impressive as any SFF build.
Doing that in 60L is easy, 35-30L would be more impressive. If you really, really tried I think it's even possible in a Cerberus-X at 22L, though the 60C part might be a bit difficult
But I agree with the sentiment, a packed 25L case is more impressive to me than a 10 liter case that's mostly empty.