I, for one, am happy to see Profanity so high on the list, even if it is less than 6%. As far as I can tell, profanity is almost always completely unnecessary, even for crass and degenerate characters. It is easy, it is ugly, it is thematically weak. More often than not, it is a crutch used to superficially raise emotional stakes and tension. I imagine that is why people drop such works, not because of some Puritanical notion. If you're using profanity, odds are good that you are missing out on better words that will not only convey what you want more precisely and meaningfully, but will be far sweeter to the mind's ear.
Otherwise, the data seems reasonable to me. Passes the sniff test, as far as I can tell. I'm shocked that "Dull" isn't like 80% of the reason people stop reading things.
For my own part, it usually is just a matter of genre and tone. I'm picky, I admit it. beyond that sort of thing, it comes down to authenticity. It is usually very easy to pick up that any given story is being written in poor faith. I'm talking about power fantasies, fetishizing revenge, intellectual masturbation--all of these things are vain, ugly, false ways of telling real stories. They're everywhere, too. Quentin Tarantino is guilty of this, as a big example. When you read a work, or watch a work, pay attention to whether it comes off as a genuine exploration of a compelling story, or if it's an excuse. There are a lot of people with chips on their shoulders. Mean-spirited people feel compelled to put their insecure rage to paper. It goes everywhich way, and as soon as I get one sniff of that kind of inauthentic tantrum-writing, I can't continue.