"The market" prioritizes short-term gains, and stratifies the wealthy and the impoverished. Allowing the market to work on products that amplify that stratification is inherently unstable.
The point of the article is that investment in Amazon is growing because Amazon has a business model built on stable infrastructure and expansion modeled as a large conglomerate of essentially separate business groups which distributes risk, and is thus better able to weather negative environments (see e.g. the stock's behavior during recent economic crises). It's being used as a hedge against volatility... in the short term. Because that's how markets operate. If you believed that you could make more money in the same amount of time elsewhere you would put your money there instead.
anyone with a spare $100
Being impoverished doesn't just mean that you're unlikely to have a spare $100 at any given time, it means that any negative life event is that much more likely to wipe out any savings you may have been able to accumulate, including an investment in securities.
This applies to any stock with a high P/E ratio.
Also, anyone with a spare $100 can get started investing in securities.