How is insulting a piece of work personally attacking someone? The work isn't them, they are not the work; it is not their person. I suppose you could argue that saying something they've made is bad is insulting their ability to make that kind of thing and thus their person, but to do so is to say that there is no difference between criticising content and contributor in the first place, which makes it rather silly to use the term personal attack in teh first place; furthermore, it is not common usage.

Also, how do you reconcile your self-identification as the '"I agree with your motives but not with your methods" anon' with the passage you quote without qualification in place of your own argument? The passage reads:

'What she's [Farla is] doing is simply trying to drive away as many people as possible.'

That looks like a quibble with her perceived motives to me. Clearly you do not agree with whoever you are quoting.

I gather Farla's PoV is that no amount of courtesy will stop people whining about a fundamentally negative view of their fic, so you might as well save time and not bother. I've generally found this to be the case myself (in the contxt of such websites); if you don't like something and say so, no matter what you say to soften the blow, the author will likely be pissed at you. Some won't be, or will pretend not to be, but there seems to be no increase in this number with increased politeness.