I would say civ knowledge probably doesn’t really matter till like 2k (this is coming from 1300 ELO pleb).
When I really look critically at my game, the vast majority of my losses come not because my opponent used his civs strengths better than I did, but because he did not mess up his build order in Dark Age.
Or he did not forget to make enough production buildings
Or he spent his resources
Or he got to castle age faster etc.
Or his Spanish archers hit my base before I had any skirms around (I did not scout) and just wrecked me eco.