The posture of a communicator
If you buy my product but don't read the instructions, that's not your fault, it's mine.
If you read a blog post and misinterpret what I said, that's my choice, not your error.
If you attend my presentation and you're bored, that's my failure.
If you are a student in my class and you don't learn what I'm teaching, I've let you down.
It's really easy to insist that people read the friggin manual. It's really easy to blame the user/student/prospect/customer for not trying hard, for being too stupid to get it or for not caring enough to pay attention. Sometimes (often) that might even be a valid complaint. But it's not helpful.
What's helpful is to realize that you have a choice when you communicate. You can design your products to be easy to use. You can write so your audience hears you. You can present in a place and in a way that guarantees that the people you want to listen will hear you. Most of all, you get to choose who will understand (and who won't).