Dimensionally stable can mean a wide range of things. To some degree, it may depend on what you are applying to the finished surface. If it was a fully adhered vinyl floor, you would want to follow the manufacturers terms because vinyl is very unforgiving. If you apply a filler or leveler on top of a peel and stick tile, the tile edges will curl up a little bit as the filler drys and shrinks.
Most fillers will adhere to particle board like gangbusters, so unless you are doing a deep fill over particle board (pressed board), I don't see a big problem as long as it is nailed well. You wouldn't want to do a 1/2 inch fill of self leveler over particle board....... way too much water involved in that situation. You might get away fine to do a fill in two layers. I think a first layer like 1/8 might cap a luan plywood well enough without disturbing it, and later to add a heavier coat one once the thin coat has dried.
Rules are made to be broken, but experience is what teaches you the limits. I won't promote hack work at all, but if you are doing laminate or pre-finished wood flooring, you will not need to apply the same strict quality levels as when you install vinyl flooring.
So if you are applying the filler simply to level out the last 12 inches at an outside wall area where you will be installing a floating floor material, then the filler manufacturers strict requirements are a bit less important. That said, you still want a stable substructure that's well nailed and not moving up and down. In this situation, a little common sense.
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Adding the plywood for fill material is better anyway. 
