Been here since early 2000s and I feel there’s always been this element to the user base, and it’s not really that much worse these days. I think maybe you had a lucky streak for a while and then hit an unlucky streak.
I’ve had really good transactions in my time here, but as I buyer I rarely haggle, never tire kick, and hold back minor complaints (this is USED gear after all); as a seller I’m picky in whom I choose to respond to. I judge them on the style and content of their initial communication, and often don’t feel the need to take things further.