You are asking three unrelated questions.
Q: Are there objectively answerable questions not answered easily by a common reference source?
A: The answer is yes, of course, by common logic.
Q: The second is, should we close all the questions that can be answered easily by a common reference source?
A: The answer is yes, as that is an acknowledged VtC reason because that practice is frowned on by SE. No sense going into all the whys, the SE crew has explained it more than adequately.
Q: What makes SE different from Wikipedia et al.?
A: Because SE is interactive, and is about experts answering specific questions, not creating general definitions. I think some of the problem is the lack of specificity - people are not asking actual questions about problems they face. They are asking general "define this, it would entertain me" questions. The SE format begins to fray when it's not real, somewhat knowledgable people asking genuine questions about actual problems they face so that other experts can help them.
Take the technical SEs as a foundation. You don't ask "what is a variable." That gets you tossed in a dumpster outside the building. You ask about a specific problem you're facing, that isn't a trivial RTFM question, and get people's help on it.
I think there's a big swell of posters into this SE and either they don't have that intent or they are masking it well.
Take this distinction.
Q1: What is new earth creationism?
That's a bad question. It's general reference, but also, it solves no problem.
Q2: My pastor told me that creationism is silly, though I believe it because of the verse in Genesis. What is some Biblical proof I can use to help change his mind?
Now, at first blush these don't seem too different. But they are different in spirit - one is being asked just to prove a point, or get rep, or "for the record", and the second is being asked for a real purpose. And experience shows that the answers one gets reflect that spirit. Question 1, you get smartypantses who want to show they're smart. Question 2, you get helpful people that want to help you (that's an overgeneralization, but it has a lot of truth to it).