It especially screwed over pre-siren Roshans (which don't seem to be much of a thing anymore). But yeah, there's still a lot the sounds can give away, like a Roshan play, a sneaky smoke, enemy tormentor attempts, etc.
Even without knowing much of anything about DotA 2 in particular: for any game with asymmetric information, the crowd reacting to what your opponent is doing is always going to be a major tell. At least in LoL, managing that information asymmetry is an important strategic element, can't imagine it being any less of an issue in DotA 2.
