So, you've hit on two long standing debates that do not have quick, easy answers. It isn't trivial to explain exactly where we stand on these issues and there are plenty of differing camps.
But here is a quick overview to get you started.
(1) So if this site is for linguists, etymologists, and serious English language enthusiasts; where do I fit in as a non-linguist, non-etymologist, non-serious-enthusiast English speaker (I am an enthusiast, but not a serious one)?
There has been a ton of discussion here on Meta regarding the target audience and whether the audience that we originally wanted is the audience that we ended up with.
And I'm sure I missed many. The short explanation is that the Tour text was written ages ago when the goal of ELU was very much to be a definitive experts site for English. Whether this is a good or bad thing is a matter of opinion.
Things got even more complicated with the introduction of ELL:
(2) If we intend to build a library of every question, why are questions closed because the answers can be found on another resource?
The General Reference close reason has also been the subject of much discussion. Instead of wading through the many, many posts, I'll just point you toward the query.
The origin of the close reason was outlined by Jeff Atwood back in 2011:
The minimum bar for a question is not “is this on-topic?”, but rather “is this somewhat interesting and on-topic?”. I’m not saying every question needs to be utterly fascinating, but please endeavor to make your questions more than a constant stream of no-duh underhanded softballs requiring nothing more than a quick cut and paste from Wikipedia, IMDB, or some other standard internet reference site.
There’s nothing useful any expert can learn from ultra-basic questions. Allow your Q&A community to fill itself with enough “General Reference” type questions and you’ll soon find no experts there at all.
This does appear to conflict with the goal of building a library to answer all questions but I think that Atwood would amend the goal to:
It's built and run by you as part of the Stack Exchange network of Q&A sites. With your help, we're working together to build a library of detailed answers to every interesting question about English language and usage.
"Interesting" is somewhat subjective but the purpose of the General Reference close reason is to set an objectively measurable lower bar for what "interesting" means. If the question can be answered quickly and definitively by the dictionary (or any other reference on the List of General References), than the question is not appropriate for the site.
Given the massive number of posts on the subject, even this lower bar is not universally agreed upon.
The contradiction I see is that linguists, etymologists, and serious English language enthusiasts are incapable of asking every question about English language and usage. In fact, this site needs beginners and intermediates, to achieve its goal of cataloguing every question. Additionally, experts cannot ask simple and widely wondered(?) questions with real purpose, because 9999 out of 10000 times they already know the answer.
The original goal was to build an environment where experts can learn from each other about a particular subject. It isn't actually to build a library of questions and answers. The "library" is a side-effect of getting a bunch of experts to dig into a subject.
To put this another way, the library is intended to serve subject matter experts. It isn't intended to fully, completely document the subject. In the case of English, there is really no reason to replicate the entire dictionary on ELU when any expert in the area is already going to consult a dictionary when it would be relevant.
This doesn't mean beginners and intermediates are unwelcome. But the beginner and intermediate questions being asked should still be asked in a manner that is interesting to answer. It is really rather boring to respond to a question that can be answered by looking it up in a dictionary. All you do is copy/paste the text into an answer and push submit. That boringness is bad. The General Reference close reason is intended to avoid making our contributors suffer through that boring work.
The remaining debate, therefore, is whether the General Reference close reason is succeeding or not. Is it doing what it should? Is it doing too much? As I mentioned earlier, there is a lot of debate on the subject. I won't add my opinion to this post — I was merely trying to explain how we ended up where we are. I'll let the others give their two cents on the subject.
