As the CTO of a small startup 0.1% downtime translates into vast quantities of lost trust and irreversible damage to our brand. Netflix goes offline for a bit they have some angry customers, and maybe lose some cash, but they'll still be chugging along. However, if we're down for a while our customers, who are already taking a risk trusting a new company, may disappear forever, and as a smaller/newer company the overall brand damage is far worse.
While I largely agree with the premise that companies over do it on infrastructure. I strongly disagree that my up time is less important than that of FAANG companies.