alt Hacker NewsThis is very context dependent. It's 'fine' having such attitude when it comes to a hobby project or personal website – not so much for ecommerce site. And imo you are missing the key part of the article – graceful degradation.
Designing for the ideal (or for the <98%) is fine. As long as the experience is gracefully degraded for the rest.
Supermarkets often have so low margin that building for the 98% of customers means that all of the profit has disappeared.
Profit is often at the margin.