I think the first thirteen, and the F&F area, can be taken too seriously. To me, as long as folks remember the heart of the practice--would you read on--it works quite well. I've learned tons from it. The problems tend to arise when it becomes to serious, as if the first thirteen have to tell the whole tale.
I gave up on my first thirteen. I just couldn't rewrite it to where people would like it, at all. The next one did a little better. The ones after were received increasingly better each time. To me, that is proof of its value.
And I agree. Of all the rules in writing, being clear seems to be among the least optional of them.
Restrict your use of adverbs and adjectives? Sure, but I've seen writers get away with it.
Don't use flashbacks? Same.
Use good grammar? Seems like the whole industry has given up on that one (exaggerating).
Be clear in your writing? I've never seen a writer get away with skipping that one.
And that clarity or lack-of-clarity really comes out in the first thirteen.
I know many here say they won't touch F&F, but unless your sure of your clarity (and sure through others feedback, not your own judgment), I'd highly recommend spending some time there. (Even then, it's worth a visit once in a while.)