Actually only one of those things hurts Blizzard… playing and visiting the forums without giving them any more money costs them to keep the servers running. Those hamsters gotta eat, you know! But, yes, definitely don’t spend any more money or buy anything in the cash shop. That directly impacts them and they might care about it.
That said they might care about player retention if the exodus was large enough. But it’d have to be drastic, like 80% or 90% just up and leaving for weeks or months before they’d start to realize there was a problem.