Probably because it treats a high-level feature (M:N threading) as equivalent to a lower-level feature (coroutines) and then compounds that by treating as equivalent languages where the former is built into the core with ones where the latter is available as a third-party library, all as a way of dismissing the value of languages where the former feature is built in to the core, and layered with scorn and derision on top of being doubly wrong.

Now, I preferred correction to downvoting, but I can easily see why others would choose downvoting.