Originally Posted by dinosaur1
Why won't we be able to?
Well technically you can, but I wouldn't suggest it.
Thinset usually never sticks to it for long, even though it's glued to the slab there are little pockets of air you can't tell by walking on it now but there there. so when you lay tile down and then walk on it there will be movement and that will lead to grout cracking then tiles will soon after shift on you.