alt Hacker NewsIt’s probably because the “create a Reddit post” form doesn’t require you to even visit the subreddit you are posting to. It DOES show you the rules/sidebar of the subreddit you are about to post to (for /r/rust it includes a link to /r/playrust for the gamers) but apparently many aren’t seeing that.
"Banner blindness" applies to the rules/sidebar. The user sees it, notices it's not what they're looking to interact with, and ignores it. The same thing happens for modal dialogues where the user will click whatever button makes the message go away without bothering to read the message, only the button text.