The point the article is making is that if you want great customer support you need to design that into the company's business model, and so it gets reflected in all sorts of places - cost structure, org chart, target market, customer expectations, etc. And then if it turns out there is a segment of the market that doesn't care about customer support (which is fairly common with tech companies), you cannot effectively compete for that segment. Tech businesses frequently have network effects or strong economies of scale, so a company with no customer support but a decent product can often eat the self-serve end of the market, then use the profits and market leverage from that to build a decent customer support operation and attack the higher-end market segments. This is the model that's been employed very effectively by Dropbox, Github, Heroku, Google, etc.
Zappos is not a software company. They sell inventoried product. The high quality support for this inventoried product is provided by low skill / low cost employees. The quality of the support staff is not in direct competition with the quality of the produced product. This is what allows it to be economical to specialize in support
I haven't heard much about Github or Heroku but as far as I'm aware, neither Dropbox nor (especially) Google have stellar reputations for customer service.
Google has great customer service if you're regularly dropping $10M on ad buys - you get a personal sales rep who takes you out to expensive dinners and does all the normal wining & dining of high-end business. I've heard GitHub is similar if you purchase their on-prem Enterprise product.
That's my point about moving up-market: it's not that the self-serve product has good customer service, it's that they create a division within the company with all the customary trappings of B2B sales & support and then leverage their consumer product as free marketing & engineering.
The point the article is making is that if you want great customer support you need to design that into the company's business model, and so it gets reflected in all sorts of places - cost structure, org chart, target market, customer expectations, etc. And then if it turns out there is a segment of the market that doesn't care about customer support (which is fairly common with tech companies), you cannot effectively compete for that segment. Tech businesses frequently have network effects or strong economies of scale, so a company with no customer support but a decent product can often eat the self-serve end of the market, then use the profits and market leverage from that to build a decent customer support operation and attack the higher-end market segments. This is the model that's been employed very effectively by Dropbox, Github, Heroku, Google, etc.