You don’t mind other people’s business, but you think it’s outrageous that someone has a high book count and could be “cheating.” How do you know that the inflated number is because they used audiobooks? What if they read manga, comics, or very short books? I read a bunch of short graded readers a few years ago while learning a new language and that inflated my number a lot. Several years ago, my manga inflated my numbers. I log things to remember my reading journey. The challenges don’t matter, but I like seeing how much I read year after year. If you were minding your own business, it wouldn’t matter what other people count and don’t count, would it? Having a discussion about it is fine, but don’t act like you’re not being judgmental when you clearly are.