D&D claims to occur in the european medieval era where magic and fantastic beasts exist.
The author's point is that it's not like that. It's a persistent capitalistic medieval themed wild west with no real power structures. The feudal power structures were a defining feature of the european medieval era.
Of course it's fantasy and can be anything. The author is simply explaining that it says that it's theme is the european medieval era, while it has almost none of it's defining features.
D&D is based on the popular conception of the medieval era. This has very little to do with the actual history that happened during the medieval era, despite sharing the same name. But D&D didn't invent the ideas it's building on.
The author's point is that it's not like that. It's a persistent capitalistic medieval themed wild west with no real power structures. The feudal power structures were a defining feature of the european medieval era.
Of course it's fantasy and can be anything. The author is simply explaining that it says that it's theme is the european medieval era, while it has almost none of it's defining features.