English is not my native language and "The solution is trivial" was meant sarcastic. The solution isn't trivial at all, nor is it complete, because solving the corner cases is complex.
I'd also like to mention ahead of time that DirectWrite/Direct2D is very fast at drawing western (Latin) text without coloring (>2000 FPS). In other words, in most situations Casey's suggestion doesn't help much, but it does address his termbench issue. At the time we assumed we were using the API incorrectly, after all Direct2D already had everything Casey suggested we should implement and it ran very fast outside of termbench. The new solution is largely identical to regular Direct2D with the only major difference being that ClearType/Grayscale gamma-correction is run on the GPU instead.
Casey's suggestion wasn't unique to me, as a significant number of other terminals do it exactly that way in OpenGl, something I was quite familiar with already. Originally I credited alacritty in the blog, because that's how I knew how to do it, but I removed it to keep the article as succinct as possible.
Update: I'm very sorry for publishing the blog post without giving proper credit where it is due, and it's been updated since. I'm sorry for my continued, overly defensive behavior.