Ah I see. decoherence as in with the apparatus, not environment (I associate decoherence with interaction with environment).
Yes, that is an explanation, but part of many that try to solve the measurement problem. Of course, if the macroscopic object is quantum mechanical, then you have issues. If you modify the Schrodinger equation, you don't generally have an issue (except it doesn't get completely localised into one definite state - as far as I've read).