I know I have problems keeping the proper usage of dashes straight in my mind, so I generally just hit the keyboard dash/hyphen key. I am more focused on the storytelling than making sure everything is grammatically correct. Inserting those types of errors into a story doesn't bother me as much as it bothers you, but then I'm not selling my product and my primary goal is to enjoy the story telling. I do my best to spot and correct errors , but if my product is not perfect, my readers can take it or leave it.
2) Readers are reading and their focus is on the content of what they read. They will typically overlook an occasional error, and the content has to be really bad grammatically for them to get upset. They are probably aware of how the standard punctuation symbols (i.e. commas, semicolons, quotes, periods, etc.) are supposed to be used. However, hyphens, dashes, en-dashes, and em-dashes are not what I would call commonly used, other than joining 2 words. As a reader, I rarely notice en-dashes and em-dashes in a story.
Now that's a more reasonable comment, so I'll respond more politely.
Yes, these 'facts' are difficult to establish, since few authors have a full research facility to document just how readers process punctuation marks. Instead, these are the basic assumptions which have developed over the past several centuries of publishing.
You don't have to 'buy' any of it, but for those of us looking to improve our craft beyond a mere 'hobby', they're important to us—especially since we're not bound to use any single Style Guide, and thus are left fumbling for which guidelines to follow and which not to.
That's why we continually argue about the topic, because it's not firmly established, but there is a LOT of anecdotal evidence that these techniques work, supported by the successes of thousands of successful authors, editors and dozens of successful publishing houses.
You won't find a single author on this site that would argue that ANY style guideline is an "absolute rule", as we're continually evaluating them on a daily basis. While we choose to follow some, there are many we've never even tried to unravel yet. This is a lifetime process, not a 'once size fits all' dictum.
So for you to attack us for insisting what's not allowed, or for stating non-existent facts is flat-out nonsense. Instead, we're simply curious and eagerly seeking the truth. You're continually belittling our efforts doesn't help, it just drives authors (and most readers) away from the forums entirely.
But the entire point of Style Guides is not to be obvious. Yet as Switch notes, if readers keep seeing the same standards being used, they learn to understand it. The 'prove in the pudding' are our Australian contingent (though I'm sure they'll object). Since they haven't been exposed to the same standards in school and in published works, they don't understand the same conventions (regarding multi-paragraph quotes and other specific structures). However, when pressed, many (Ernest at least) have admitted many of the books they have read actually does follow these standards, which again emphasizes that these details are both culturally bases (i.e. Western vs. Eastern), and that Styles are NOT intended to be 'noticed'.