Far too often I see mundane medieval labeled as "Fantasy". It's not Fantasy unless it has fantastic elements. You can have Low Fantasy, Urban Fantasy, Fantastic Horror, Romantic Fantasy etc but it has to have fantastic elements. Having knights and princesses in a civilization that resembles Medieval Europe does not count as Fantasy. I don't understand how someone can make that mistake. It's infuriating.
I assume that this misconception comes from the fact that traditional fantasy stories are set in the distant past and especially the Medieval European period. Back then you had priests that claimed to draw power from various gods, magicians with their spells and potions, wide-spread beliefs about a bestiary of monsters and spirits that roamed the countryside. It's easy to place a fictional story about evil sorcerers and dragons and other such supernatural things in such a setting and this setting also contains knights and princesses and other mundane things that go hand in hand with the supernatural. Therefore, it's easy to accept that they were associated over time and then lumped together further once society moved from the Medieval to the Modern. Some stories go as far as to state that the two are incompatible. TvTropes has several entries for this sort thing:
1. Magic Versus Science-The two are seen as rivals either in their operating principles or in their users.
2. Science Destroys Magic-The two literally cannot coexist.
3. Doing in The Wizard and Doing In The Scientist-One is explained as the other.
There are more but I believe I've made my point here. Scientists are seen as belonging to the Modern Era and Wizards/Witches/Magicians etc as belonging to the distant past. This is why I can understand someone calling a Medieval Setting "Fantasy" because even if there is just superstition instead of the real deal, it can still count as a fantastic element. I understand it but I don't agree with it. Unless it's real it doesn't count.
On one hand it's a matter of being accurate. I have different expectations of a Fantasy novel and Historical novel and I want to know which one I have in my hands before going in. On another hand, I feel like it's a cheap marketing gimmick to draw in readers.
I once had a review request from someone who had zero fantastic elements calling their story "Fantasy". I asked him about this and he replied that his events "were implausible" in real life and that it was made them "Fantasy". Furthermore, he said the fantastic elements would make his story cliché. He wanted to be unique, not predictable and for that reason he didn't add fantastic elements. The result of this is teenagers fighting terrorists with toys. How is one supposed to accept such a premise? I imagined all them getting gunned down in their first confrontation. The third point was the most upsetting; he said that adventure and heroism made it "Fantasy" and in this way claimed that any story with a Hero's Quest/Journey is automatically "Fantasy".
A "Hero Quest" does not make something into a Fantasy! That can exist in any story of any genre! Joseph Cambell proved this with his model of the Hero's Journey. It is a universal template: "Supernatural Aid" does not have to be from a god or a fairy godmother but from a mundane and earthly friend or parent or anything like that, nor do "Threshold Guardians" have to be a troll guarding a bridge, it can be a bully or a test or something else mundane. "The Unknown World" can be a mysterious forest, a new school, or simply a changing social environment. Challenges, danger, and courage are things that exist in many genres, not just fantasy.
This is why I don't accept review requests from people that push a "Fantasy" novel that is clearly not Fantasy.