As another homeschooler, there is a fine line between gauging interest and imparting self-discipline. Of course, such "hard work" looks radically different at home than it does in the classroom. It's important to teach your children that there are times when they need to focus on things that don't necessarily interest them, but, again, how this is carried out in the home would likely be more positive than a classroom setting.
That said, I agree with the parent, and the original blog post. Our older son picked up reading and writing quickly (without much prompting from us, but his younger brother is less interested in those things, but is showing greater creative ability, so we're running with that.