They bury the important point halfway through the article: Amazon is a free-cash-flow machine and it has almost always been so. The distinction is subtle [1], but consistent (and ideally ever-growing) free-cash-flow is what really matters in valuing a highly capitalized company, even if the firm has always re-invested it each quarter to date. The important point to investors is that the firm's re-investment is a decision -- the company is not brittle to economic downturn and any quarter could decide to payout investors through share buyback etc.
Copious free-cash-flow every quarter is why software companies generally have higher valuations than traditional industries and why it was novel that Amazon, which is not obviously a software company, behaves as one financially.
Copious free-cash-flow every quarter is why software companies generally have higher valuations than traditional industries and why it was novel that Amazon, which is not obviously a software company, behaves as one financially.
[1] https://www.investopedia.com/terms/f/freecashflow.asp