Most of the time when you accept input from the user the very first thing you do is pass it through a HTML encoder.
I don’t know if you worded this poorly or if this is actually what you’re doing. But that’s not the first thing you do when you accept input. It’s the last thing you do before you output said input to a HTML page.
If you wrote this blog software that way then that’s probably why Andy’s link is garbled up above.