Awesome (old) post by Chris Taylor about progressive enhancement, seen as Technical Credit:
With such a wide array of both expected and unexpected properties of the current technological revolution, building our systems in such a way to both be resilient to potential failures and benefit from unanticipated events surely is a no-brainer.
Unfortunately, it seems most people working in Web development, at least outside our Web quality standards bubble, don't seem to grok the importance of progressive enhancement.