CJ: I like your question, "Do we write for every idiot that wants to read our books...
Repeat your "facts" at least twice and keep them few. In court, circumstantial evidence is not numerous in quantity but can alone be enough for a jury to convict if placed in several different contexts. The gloves are proven to be purchased by the accused; the gloves were seen to be worn by the accused; forensic evidence shows the gloves found in the accused's apartment contained the victim's blood; etc. The "fact" repeated in different contexts, the gloves owned by the accused were instrumental in the murder of the victim, is yet still a single fact, but perhaps only with another such "fact" can be proof beyond a reasonable doubt. An author creating the mystery would walk the reader through each of these aspects of the reality of this "fact." Law and Order and CSI, limited in time and audience attentions spans, did a decent job of creating such solved mysteries. Mystery-crime novels, on the other hand, spin too intricate a story in my opinion because (also in my opinion) female readers like a lot of senseless blather in their stories.
The nice thing about beta readers is that it reminds me of Fritz Leiber who, before he was a famous published author, corresponded with another would be fantasy writer. They would exchange stories, and ended up writing for the other. Leiber would go, "Wait until you see what Fafred did this time," or "What do you think of the Gray Mouser's new girlfriend?" It's nice to have interaction with readers.
There used to be a game played in some English-lit classes of every student in turn contributing a part to an on-going (in theory, never-ending) story. It was a great exercise in creative ad-lib story writing, in a sense like a mystery never solved, because the previous writer would often simply make a change for the sake of making a change. The stories themselves ended up being pretty awful creation-by-committee art.