> "Why do you people always presume they know what is best for other people?"

Well. Let's examine the context of the conversation. You replied to the statement "Don't like porn? Cool, don't buy it or avert your eyes!" with "Why do you then tell others how to live their lives? Is really leaving everyone to their own devices the good idea?"

Most folks have a healthy relationship with porn, and a reasonably-healthy relationship with sex in general. Given that the US is a reasonably-free society, its default stance is "Mind your damn business, and everyone else will mind theirs.". You rejected the call to avert your eyes from something that is moderately offensive. This indicates that -when it comes to porn- you're not content to mind your own business while people quietly go about their own. This means that you are the busybody poking his nose in other people's business.

Thanks for clarifying. I now see where the disapproval comes from.