"template" vs "backdrop" <= isn't this some sort of weird semantic quibbling however? These terms in these sorts of discussions clearly aren't going to have any specific objective meaning.
It's kind of semantic, but it's the foundation of the discussion right now. So (if we ignore that everything we're doing now is ultimately just a meaningless way to fill the time before the final release of death, and all meaning is but an illusion) it's a fairly important distinction.
By a "template" in this context, I was referring to the rough idea of "one guy, X number of girls + situation", nothing more or less. Maybe that's a "backdrop" to you, but a "template" to me.
Well, that much is so vague and general as to be meaningless; that a series has a situation is a given, and the gender ratio says very little about dynamic, which I would consider the important defining feature of a harem. The "classic harem" would be the case in which the male, a nondescript Japanese youth, is the object of poorly expressed and often repressed romantic affection of the girls, which he does not openly reciprocate, though due more to social cowardice and incompetence than necessarily a lack of interest. Hijinks ensue.
But to me, I'd only use "backdrop" to refer to the setting, e.g. the backdrop is a space station or fantasy world. To me, the "backdrop" is more constraining of content than a story structure/template would be.
A template denotes a structure, an overarching thing with blanks which are filled. It is inherently constraining of content, and implies a strong unity of the main elements of the work with those of other similar elements. I used Dresden Files as an example earlier; forgive me for doing so again, but that's an example that uses a template well: The story always follows the same pattern, only the details are different, and yet each book is enjoyable. The works of Ken Follett don't always use the same overarching plot structure, but similarly share a lot of common elements that might be called a template. And pulpy romance novels do this even more strongly and across authors. Some harem anime do as well, but I think that's actually a rather small subset of the series which could be considered harem.
To refer to the setting, personally, I'd use the word "setting". I would consider it more constraining of aesthetic than a structure or template, but less constraining of narrative. Either of those could be called "content", which is a very broad term.
A "backdrop" implies the painted backdrop of theatre, which sets the [situation], but says nothing about what the story itself will be
Note how small a change I made to your definition, which makes it apply to the use of the harem in Punchline. Actually, I think there is an even smaller more appropriate change, but I can't come up with the phrasing.
Neither term has an objective meaning in this context either way. It's not worth carrying on a conversation if it's going to devolve to nitpicking over semantics though.
Well, I would have thought my usage was more or less consistent with general literary application of the terms, although literature isn't really my area of study, but no language has an objective meaning; it's all consensus-based so it occasionally is necessary to verify that we do have consensus. I suppose it's hard for me to assess the worth of a conversation; I would hold it to be intrinsically valuable (if we ignore that value is a social construct) but I don't think going over some definitions and terminology is necessarily just nitpicking, even if we have gotten a bit off of our original topic, as does sometimes happen in the course of discourse.