Quoting from the author of the blogpost:

"We actually took the same approach Casey suggested... A lot of terminals implement it that way." [1]

I guess authors of a lot of terminals are trolling you.

From the refterm README: "VT codes for setting colors and cursor positions, as well as strikethrough, underline, blink, reverse video, etc." [2]

And, to begin with, Windows Terminal was horrendously slow even without VT codes. Also, for context, [3]

[1] https://news.ycombinator.com/item?id=31285723

[2] https://github.com/cmuratori/refterm

[3] https://news.ycombinator.com/item?id=31285339