It isn't really lack of growth that's a problem, there are tons of companies out there that post a very consistent profit quarter after quarter that are doing just fine - negative growth, especially in a few of a company's core segments, is just as unsustainable as positive growth year over year is. If you have enough quarters of negative growth, very soon you have nothing. It is a warning sign to investors that things might not be going so well. Is one or two quarters of negative growth bad? Probably not in Apple's case, probably yes in something like AMD's case. The context matters, but there is a reason growth is used as a metric, the market is not stupid.