People that think your comments are the totality of you

People having this need to look through your posts and comments and thinking that that fully represents you. Yes I look at porn on here, but that doesn't mean that's all I do. I just don't use alts. I comment on multiple things but people see comments on those subs and suddenly think all I do on here, no matter the sub, is something to do with porn. Why do people feel the need to go through comment and post histories, why can't you just respond to the comment without mentioning other things the person does?