Should prominent modding communities be given their own site and if
not, what is a better alternative and why is it better?
This is not a discussion that is appropriate for the Game Development community; this community can discuss the topic of whether or not this site should be hosting modding-related questions or not. Area 51 is the appropriate venue to discuss whether or not modding, or game-specific modding, should have it's own site. That happens independently of Game Development.
Given the reasons I proposed, should modding be covered by GameDev.SE?
If so, why?
The subject is already on-topic; the community doesn't need to re-iterate why it should be. Instead, you (or others who agree with your position) need to provide compelling reasons why it should no longer be on-topic and win a community consensus.
When talking about whether a specific existent subject should remain on-topic on a specific SE site or not, you generally need to address two issues:
- where that topic might otherwise be on-topic, if anywhere and
- why hosting that topic actively harms the site community or is otherwise detrimental to on-topic subject matter elsewhere on the site.
In the case of modding, it's not on-topic at gaming as of this writing, and that's probably the only other reasonably site that would cover it. So there's no basis for banning it here on the grounds of "it's covered elsewhere."
The crux of the issue, then, is: does it harm this site? I don't see any hard evidence as such in your post. Only opinion and conjecture. I'm therefore not particularly inclined to agree with you.
You say that the main reason you think modding should be off-topic is that the audience isn't there or isn't suitable to answer the questions. But of the 100 or so modding questions we have, approximately 80% have at least one answer. That doesn't seem like an unhealthy metric to me. Further, "audience size" isn't a good reason for banning a topic anyway; a small audience for a subject is rather an opportunity for the site to attract more users. We don't want the user base of the site to become stagnant or to get too much of an "in-crowd club" appearance, and supporting a diverse range of topics is therefore ideal, even if the practical audience for those topics is not currently large. We also expect and desire users with lots of different areas of expertise; not all users may have familiarity with all mod tools, but not all users have familiarity with all graphics or physics APIs either (and so on). There's absolutely nothing wrong with having pockets of non-intersecting expertise on the site. It is, in fact, desirable.
Your arguments regarding culture seem mainly to do with terminology, which is already an issue within the realm of game development and is easily handled by asking clarifying questions to provide specificity in the use of terms that may have different meanings in different contexts. The relatively slow growth of modding-related questions and users focused solely on answering those questions doesn't cause me any concern that there will be a sudden significant shift in jargon on the site that will create a Tower of Babel effect.
You are welcome (and encouraged) to start a game mods proposal on Area 51. But I don't see anything in your argument here that would make me think we should reconsider our stance on game modding questions on this site at this time.