There is, but not in that way. The risk of crushing is always present with carbon components; they should always be fastened to mfg specs using a torque wrench. That applies to stem bolts (or bar ends) as well. The 'compatible' business really had originally to do with another potential problem: many stems are crudely finished at the stem/bar interface -- sharp edges, burrs and such. These can score the fibres in carbon bars eventually, which can lead to failure. Typically all that 'carbon compatible' stem really means is that the surfaces are properly smoothed. It can also refer to four-bolt vs. two-bolt bar clamps (spreading the required force over a larger area).