This is true!
Generally speaking mobile homes don't possess the structural criteria suitable for a rigid floor covering such as ceramic tile. This isn't to say it is never done, heck they even put ceramic tile in high-end motor homes, I know because I have repaired many many many of them over the years.
The partical board would have to be removed totally. Marine plywood IS NOT necessary, that's just plain stupid and a waste of money but that's the kind of unknowing-information that comes from Home Depots.
Exterior grade plywood however would be necessary and then a suitable tilebacker (cementboard) on top of that. The absolute minimum is this case would be 3/4" exterior plywood and 1/2" cement board before the tile. Then a modified thinset and a modified grout. The cement board would also get set into thinset and fastened every four to six inches in all directions.
Then you will have some transition issues (to the rest of the room) and you need to varify that your door will clear the re-elevated flooring and after all of this every time the wind blows the tile and grout could still crack.
In my opinion there are better choices of flooring for a mobile home.