Maybe you could post a notice or something on your site, that you don't "require" begging feedback and that it won't make you write faster than you already do (something phrased politely of course, so that it doesn't come across as being snobby about what kind of feedback people should write). I mean, readers can't really guess which authors have which preferences in this regard. Obviously there's no way to prevent anyone from writing any kind of feedback they like, it's just like with authors who have a note that they'd prefer not to get negative feedback, but I guess people who think the "normal thing" is that authors want as much begging feedback as possible, might not write like that when there's a note explaining things.