Earlier quoted context omitted.
"some anon on a tech forum" Don't sell yourself short. Post some art from those 800 years that doesn't suck, and I'll change my views. Sure, there's plenty of crap in 20th century art. I've seen examples of that. But that's a different subject.
Like I said, I find the majority of European art before 1800 or so to be fairly dull, so I can't really answer this question. The prevailing technique improved remarkably post-Renaissance, and that's enjoyable to an extent, but the same themes get repeated over and over and over again. If you're looking for art with an impact, the iconography of Andrei Rublev (and other icon painters during this period) is still mass…
Andrei Rublev, 1360-1430? This dude? https://en.wikipedia.org/wiki/Andrei_Rublev#/media/File:Rubl...
Yeah he's good, that's obvious. Klimt cribbed from Rublev I bet. Naturalism was never the topic. But note that Rublev didn't do much work between AD500 and AD1300. Because not born yet. This is precisely why I wrote down dates, and why I am insisting on counterexamples instead of vague generalities.