I've seen that too, though I have to say that none of those were as waterfally as the actual waterfall process we used to follow. Back then it was quite literally 0 lines of code until spec (100s of pages) is complete.
Which ironically makes Agile even worse at times by forcing developers to implement incomplete spec, parts of which are often rewritten over and over again everytime the PM talks to the client.
Which ironically makes Agile even worse at times by forcing developers to implement incomplete spec, parts of which are often rewritten over and over again everytime the PM talks to the client.