There are so many questions about Minecraft they would fill a site, and most of them are trivial to answer. I regularly go on Arqade to answer questions, but Minecraft dominates the place.
Yes, there are a lot of Minecraft questions. This is just because Minecraft is a popular game, so naturally a lot of people will ask for help. And as you say, most MC questions are out of scope for this site. As you can probably tell from the sidebar, this is a pretty common problem people have, and unfortunately there is no easy answer. The problem with a dedicated site is that it's still going to have to fit the rules of the network, which means that most of the questions on that site are STILL going to be off-topic and closed as such.
And that's just the fact of the matter. Yes, a lot of Minecraft questions are low quality or duplicates. Most of them are asked by entirely new users who don't know how the site works and probably just found this site somewhere. If you check some of the recent users, you'll actually notice A LOT of them (probably close to a third, if not more) are actually online content creators who are probably looking for ways to expand their audience, and they think that our site might help them in that. I think we might have more success focusing on that front.