Only 20% is why the stock is down after hours, at 100 P/E AMZN is speculatively priced where they're expected to achieve infinite growth until they deliver financials that justify their valuation which Investors are betting on to happen before they hit any growth ceiling. There's also no room for an economy downturn which expensive stocks like AMZN are extremely volatile to.
Growing 20% at Amazon's size is why the stock is worth so much. Almost all companies have slowed down long before this point. Amazon is still growing like a late stage startup. It's really a remarkable feat.
Are Facebook, Google, Microsoft also still considered late stage Startups?
FB Growth 28% YoY, P/E 26.51, Mkt Cap 573B
GOOG Growth 19% YoY, P/E 25.90, Mkt Cap 788B
MSFT Growth 12%, P/E 27.69, Mkt Cap 1.07T
They all have a much more reasonable P/E. Agreed that it's harder to achieve growth from a massive base, but they're also priced from being able to continue doing so much better than their competitors.