Could you clarify what you mean? They explicitly compare against LaTeX, on which Overleaf is built, and I don't see any points in their comparison which are mitigated by specifically using Overleaf.
Typst looks cool, and I'm probably going to check it out at some point, but a comparison to similar web-based LateX solutions would be more useful than what they have at the moment is all I'm saying.
The compilation speed of LateX doesn't really compare to Typst. With Typst I can work with 3 other students on the same paper, and all of our keystrokes are immediately rendered.