"Agile methodologies killed the specification document long ago. Do we really need to bring it back from the dead?"

Not at FAANG. Or at least not at Google where I was for 10 years. They were obsessed with big upfront PRDs and design docs, and they were key to getting promotion and recognition.

These days those kinds of documents -- which were laborious to produce, mostly boilerplate, and a pain to maintain, and often not really read by anybody other than promo committee -- could be produced easily by prompting an LLM.

Having drunk the well-spring of XP and agile early in my career, I found it continually frustrating. Actual development followed iterative practices, but not officially.