Help explain newbie quesyion

[LDu]

Newbie question. So my uncle is trying to reinvent the wheel. I know what he is doing is wrong. But can someone explain to my why his method does not work. He is applying large amount of thinset directly on the back of the tile and pushing it down on the concrete. He is not trowling on the concrete and setting the tile on top.
Please explain

 

[Boggs]

Get your uncle to watch this.

 

[J Sid]

The adhesive needs to be applied to concrete as well as tile to create a solid bond between tile and floor. Yes he could trowel the tile and butter the floor but is quicker to butter tile and trowel floor.