The modern web on a slow connection (2017)
From a capitalist devil’s advocate point of view: does it really matter that your website works poorly with 90% of the web when these 90% either don’t have any disposable income (there’s got to be a correlation) or are too distant geographically and culturally to ever bring you business? The “commercial quality” (i.e. to avoid looking worse than competition) web development has become unbelievably complicated and expensive, so in reality probably only individual enthusiasts and NCOs should care about the long tail. Local small businesses will just use some local site builder or social media, so even they don’t matter.