I consider Project Quintessence to be primarily science fiction, but it does have fantasy elements. It’s just, the “magic” and golems are given “scientific” explanations, making it more soft sci-fi. And with the modern setting, it’s closer to urban fantasy than fantasy fantasy. A story that was primarily set in Ertiada’s world would be much closer to what people mean when they say “fantasy” without qualifiers; a fictional world that has things that aren’t possible in reality.
But some people seem to think it’s a lot more specific than that. Some people insist that fantasy worlds have to resemble medieval Europe, complete with feudalism, sexism, and a notable lack of humans that aren’t white. (Actually, that last one is often taken too far even for medieval settings, since there were minorities in Europe in the Middle Ages that were more closely to people in Asia than to anyone else in Europe.) There’s a growing trend of “fantasy” worlds that don’t even have enough magic to explain why technology would be slow to develop. (Since most of these fantasy worlds have long histories that suggest they’ve been stuck in a feudal age for a lot longer than feudalism actually lasted in real history.)
This is one way where video games, especially Japanese RPGs, have the right idea. For example, while every Dragon Quest game does lack guns and forms of government that aren’t monarchy, there also isn’t a single one that really had feudalism. Dragon Quest III, where the world map is full of parallels to reality, is closer to the age of exploration than the middle ages, and Dragon Quest VII has steam-powered automatons. Skies of Arcadia is another age of exploration one, in a big way. Final Fantasy VI and Lunar: The Silver Star’s settings are closer to the industrial revolution than any other real era, the Wild Arms series is like the wild west, and Phantasy Star has space travel and laser guns. But all of them are also essentially fantasy stories. (The first Phantasy Star, anyway; later ones, especially the second one, have more science fiction and less fantasy/mythology.) It’s also common in these games for there to be a lost ancient civilization with more advanced technology than the current one, which is a post-apocalyptic element even if the setting often doesn’t fit that description overall.
I’m not saying that all western fantasy fiction is medieval; I just read a pioneer one recently, and of course there’s Avatar: The Last Airbender and The Legend of Korra, which also avert the silliness of not having technology advance over time within the setting. But the “you are doing fantasy wrong if you don’t have (insert fact about the middle ages)” attitude seems to be mostly associated with western fantasy literature.