I wouldn't lie; I sometimes skip long posts when I can't manage the time. But does that make me feel guilty? Yes. Because I feel like I'm not giving the person the attention they deserve.
But again, it's tiring to read long posts and comments.
I agree that people mock for making something lengthy, and oftentimes, the long poster doesn't add much but repeats.
I believe readers should not be the judge. If it doesn't suit my taste, it's better to move on rather than mock someone. And yes, fortunately, it's different online.
After all, it's an open space, and every one of us owns the world.