Think about how silly that statement sounds.Thinset for smaller pieces...under 12x12 or so.
For support or pieces over 12x12 or 16x16 use(r) mortar.
Don't be an anus grasshopper. Methods change and improve with time. You are going back fifty years or more. Get with it man, update your brain.
If you aren't willing to learn then you aren't living up to the name grasshopper.
Think about how silly that statement sounds.