Not quite the right question, I think..? Does it affect the sound..? Yes, to a lesser or greater extent. Does it adversely affect the sound..? Not necessarily. Any acoustic instrument sounds as it sounds. f that's the sound you're after, then that's fine. If, on a full-bodied acoustic with a pleasing sound one could get out the band-saw and cut a chuck off for access to the high notes, the sound would, in all probability, be severely impaired. If, however, the guitar was designed and built that way, taking into account the cutaway, the result would very likely please a least some of the customers for that guitar. The reply, then, is really : if it sounds fine as it is, it sounds fine. There are many acoustic guitars with this feature, many of them sound great.
It's also true that many guitarists wanting/needing this feature play through amps, or record with the built-in electronics. This, too, alters radically the result, as the sound is no longer merely a function of the acoustic properties, but a sum of all the elements used. In that respect, a cutaway has little bearing on the phonics in absolute terms; again, if it sounds fine in the end, it's fine. Whether one plays up the neck or not, it's worth giving all guitars a listen, to appreciate their qualities.
Hope this helps.