1. Successful agent (or editor, or author) says or writes about a personal preference they have, such as, "Good characters must have flaws." They may or may not support this statement with any evidence or examples.
2. Because of the status of the above, other agents, editors, and aspiring authors hear this statement and repeat it over and over again until people just sort of accept that good characters must have flaws.
3. Result: the CW that good characters must have flaws is established and to write a character without a flaw is to brand yourself an amateur hack.
You can find more on groupthink here: Stuff about groupthink, but I think this sums it up pretty well:
Groupthink is a concept that was identified by Irving Janis that refers to faulty decision-making in a group. Groups experiencing groupthink do not consider all alternatives and they desire unanimity at the expense of quality decisions. Groupthink occurs when groups are highly cohesive and when they are under considerable pressure to make a quality decision.
Now to questioning the popular belief that first lines have to induce in the reader some sort of hypnotic trance whereby the reader is so enchanted, so "pulled in to the story," that he could not possibly conceive of putting the story down even if his house was on fire.
First, you may be tempted to question whether or not this advice about first lines is, in fact, conventional wisdom. If so, do a quick google search. I searched "writing first lines" and received 13.5 million hits. By comparison, "writing endings" will get you about 2.5 million. If you take a look at any of these links you will see that there are contests for writing great first lines, there are message board posts written by writers who are near tears because they just can't write that first line. There are writers who lament that they'll never be able to write their novel because the whole thing flows from that first line and, damn it all to hell!, they just can't come up with one.
It's all a bunch of hooey. And I will now prove it. Below I have listed the first lines of some very good novels. Award-winning novels. Without using The Google, see how many you can name and then ask yourself, how important to the overall story was that first line? Ask yourself, based only on this first line, do I absolutely have to read more? Ask yourself, if I was running a first line contest on my blog, would any of these even get a second glance? And finally ask yourself, should I just accept it as truth that first lines have to be everything people make them out to be?
- A mouse was looking at Mario.
- Once, in a house on Egypt Street, there lived a rabbit who was made almost entirely of china.
- Mr. Utterson the lawyer was a man of a rugged countenance that was never lighted by a smile; cold, scanty, and embarrassed in discourse; backward in sentiment; lean, long, dusty, dreary, and yet somehow loveable.
- It was Sunday after church and all my chores were done.
- Mr. Verloc, going out in the morning, left his shop nominally in charge of his brother-in-law.
- Gramps says that I am a country girl at heart, and that is true.
- Dusk--of a summer night.
Now, it should be understood that just because the CW is wrong does not mean it isn't good advice. I like flawed characters. But that does not mean that all important characters must have flaws. I like a compelling first line, but that does not mean that you can't write a great book without one.
In the interest of fairness, I should also state that most of the books I looked at did indeed have a very good opening line and let me repeat, I like that. But just because I like it and just because a lot of readers like it (and one must ask if we've been conditioned to like it, mustn't one?) and just because agents like it, does not mean that a book must have one. Is it a good way to start, sure, but it shouldn't be a litmus test used to weed out good stories from those that are not.