Skipping a moisture barrier or tile backerboard can motive water ingress; spend money on cement backerboard
https://hotel-wiki.win/index.php/Why_Phoenix_Home_Remodeling%27s_Bathroom_Renovation_Process_Feels_More_Organized_in_Sun_Lakes
Skipping a moisture barrier or tile backerboard can result in water ingress; put money into cement backerboard and tile underlayment to preclude warping and mould improvement.