the bit at the end is quite rude of the haskeller responding but I also think they're largely right; another monads explained through boxes tutorial is not gonna help anyone. In fact it's really a step in the wrong direction. Using a few different monads is where to start.
Was it rudeness or honesty without malice? The "monad tutorial" instinct is a well-documented fallacy. In my culture we don't whitewash our opinions to make them palatable to someone who's obviously doing something wrong in a known way.
On first read, I was prone to agree with the author -- why put down someone seeking your input? Then I read your comment and went through it again. After a re-read I think you have it right. The response was direct, and perhaps quite cutting to the author who had devoted significant time to the article only to be told they're one of hundreds who have made the same mistake. But the only denigrating in the linked blog article seemed to be the grouping with others who had fallen into the same trap.