The obvious conclusion that I think we can both agree upon is that different readers will have different expectations of the books they read, are willing to accept different levels of (in)accuracy if they find other aspects of the book enjoyable, and will be bothered by different types of mistakes if those pop up. The threshold for what is believable, or what sort of things that are less believable are nonetheless acceptable, is bound to differ. I don't know how you determine whether dialogue is anachronistic or not for authors writing in different periods, but I'm not going to argue with your conclusions.
I can't stand it when "gender" is used incorrectly or anachronistically, either - and it's worse when people think an ultrasound will reveal their baby's gender. Um, no, sorry, you'll have to wait for that.