Let's start at the top of this.
What should a writer be doing?
A writer should be being true to themselves, because there's no point otherwise; they should have an eye on their time and mental health, because writing tends to diminish those; and they should keep an eye on how their work is received, because there's no point trying to communicate if you don't check whether it works.
Lists like these have don't really have a place in the first.
Lists like these are actively, if minorly, harmful to time, and potentially quite harmful to mental health. The average writer spends enough time worrying over everything they do without encouraging worrying about the tiniest of details. Look at how many threads there are here asking permission to do this or that. I have known people who've made themselves genuinely quite unhappy stressing over writing advice.
Which leaves us with communication and this point
Are you suggesting that It Ends With Us sold 2.7m copies because it used italics?
A good book can have annoying details. They are annoying even if the book sells well and is loved. If you are writing a book sure to impress no matter what you do, don't worry about it. But maybe folks who aren't so certain of their success might consider unloading stuff that's meh.
My main feeling is that being given access to other people's tastes is a good way to examine your creative assumptions. Not treat them as rules.
No.
I am stating that as a guide as to whether italics are an actively bad and annoying thing in terms of writing fiction that people will like, the book that sold 2.7m is far, far better than the one survey done on a newspaper's book club mailing list that got "hundreds and hundreds" of respondents, and from which data we got to see a brief, imprecise summary and a few quotes.
The former is a copperplate guarantee that it won't annoy people enough to prevent a book from becoming a massive seller.
The latter is functionally useless. Did 20 out of 200 people complain about italics, or 2 out of 800? Is it just something that bugs them which they took a chance to vent about one day but doesn't stop them liking and recommending books at all, or something that does really turn five star reads into one stars? What genres do these people even read? This list isn't even being given access to other people's tastes in the first place. It's like finding a torn off piece off their groceries receipt and trying to work out what they like to eat.
And even if it was doing that, so what? Being the most successful fiction book in the USA last year meant selling to less than 1% of the population. You can afford to take choices that alienate huge swathes of people and still get yours. Which is just as well as if you ask enough people for their pet peeves, you will find that absolutely everything is on the list soon enough. The exercise is pointless to begin with.
Smart writers don't worry about how they'll annoy people, they focus on how they'll make their audience happy.
Since I have devoted far too much time to this, I will indulge myself in a coda -
Good writing involves constant self-challenge. We are often turning to people and asking questions every day. My rubbishing of the idea this list has value for writers is not a rubbishing of the idea we need to examine our creative assumptions.
What good writers recognise is that given the endless list of ways to examine our creative assumptions, and the extent to which these methods are not one size fits all, they must pick smartly. Developing writers need to learn to exercise their judgment about what helps and what doesn't to become good writers, but they also need protection from the stuff that doesn't help.
As such, it's barely possible to criticise the idea writers should pay attention to lists like this enough.
they promise a completely untested set of results that come down to nothing in terms of demographics. Who takes these polls; why are their opinions so poignant? 
