Statues were typically large and outdoors and viewed at a distance, frescoes were typically viewed in close proximity and needed details adding to not look completely flat. Some of those also were rather "garish" compared with modern tastes, particularly when freshly painted and not after years of fading and being covered up (and very sensitively restored according to protocols which frown on adding pigment)

I did find it odd that there was no discussion about whether those other media now represent the exact colors that they had when they were originally created. I know from experience that colors fade, but the argument seems to ignore that.

I also know that most of the old paintings that we have today have been though multiple rounds of "refreshment" in order to counter both the fading and dirt/soot that they were exposed to over the years (remember: most of these were displayed by torchlight/lamplight/candlelight for centuries). Nowadays there is a real emphasis on trying to produce an original ascetic, but that has not always been the case.

So I would want a better discussion of how accurate those "standard candles" are.