I just did a very informal poll among friends I have who do not edit Wikipedia, but who read it, on the matter of when an article should be deleted.
I did not express my own opinion to any of them and solicit agreement. So the fact that they are my friends so, naturally, they agree with me doesn't play into this. On the other hand, the possibility that I am naturally prone to talking to people who basically agree with me, even on issues we haven't discussed, might.
In any case - no one I talked to mentioned notability as a reason to delete. All of them, upon being specifically asked about notability, generally took a "whatever" approach to it, with several specifically saying, "No, if the article isn't lies, it should definitely be included no matter how trivial the topic." Other views included "If the topic is mentioned in another article, and that mention wasn't created specifically to make an excuse to have an article, it should be included" (The closest thing to a deletionist position I got) and "If someone cares enough to create it, it should probably not be deleted, even though that someone might be being an idiot."
Which doesn't prove anything, I'll be the first to admit. But I think this is an important thing we haven't been asking - what do readers think. Most of the people expressing their opinions on this inclusion/ exclusion debate are editors. Most of us, in fact, are very jaded editors. And we are an incredible minority among the people who load en.wikipedia.org every day. And we should bear that in mind - because after a bit of talking to readers, I think people really do want us to try to be a place where you can find any piece of knowledge or fact. To a degree, actually, that's even beyond what I think is important to achieve (Although I still would rather leave in garage bands than exclude notable but obscure topics, and I still don't care enough to delete garage bands myself).
-Snowspinner