Waterfall specifications have never worked as advertised.

The 1980s and 90s were full of DOD-497 multi-kilogram documents being analyzed atomically to determine the specification, and they rarely came in close any of the 3 main dimensions of success: time, quality, or cost.

On the other hand, neither has Agile with a capital A, with the ceremony of documents replaced with the ceremony of JIRA tickets and t-shirts.