Because someone here is incapable to think wide.
Kaido blitzed Boundman G4 Luffy back in the day.
Unless you guys believe that Law will babysit Zoro to manage to land his attacks on Kaido for the latter not to dodge, Zoro is in all likelihood at least faster than that version of Luffy, for what it concerns combat speed in general, not even necessarily movement, just like Snakeman was.
So being so confident that Zoro can't break through FS is straight up ridiculous.