One reason I can think of for not using construction adhesive is that the volatile chemicals in it could absorb into a porous tile and change the way moisture releases or absorbs into it. Using it to bond certain stone materials can definitely cause that problem. Saw a contractor tear down a huge verneer job one time because his guys used the wrong adhesive.
awww gee whiz, i think a little humor helps spice up some of these dry threads..... *grin*
but, THAT'S an answer that makes a bit more sense, tnkx m6
(i had thought maybe the adhesive could leech through from the back and stain the tiles)