Interesting take. I look at it as less “anti-medieval” and more anti-government. Gygax was a libertarian and it grew out of wargaming. Gygax just wanted a world where he could fight dragons and didn’t bother to do the world building of an economic or political system. I think this was more out of disinterest in the topics rather than as a political stance.

IMO, the big American bias in heroic fantasy RPG including D&D is how empty (most) settings are. If you travel (nowadays by car) in rural Europe, you’d find village every 5-10km, turns out that people walking to their field don’t like to spend more than 1h commuting. While on some high fantasy map, you have like 3 day of walk through a dangerous forest, or an endless plain without much settlements.

Also it’s worth mentioning that many European major roads/highway have been built at first by the Roman, and have been modernized through history. So again, middle age wasn’t as empty, salvage as many D&D settings. Which indeed looks more like frontier era US.