The one thing waterfall did that I think was actually quite a good thing, at least for larger scale problems, was 'preliminary design'.

Experience shows it's really important to get 'the bones' of your system right, as early on as possible. Working to produce a preliminary design in an abstract space rather than in code frees you at this early stage from the inertia of code. It's easier to throw out a set of block diagrams and start over precisely because, as mere diagrams, they don't "sort of work already". And I'm certain that in the history of waterfall projects, nobody anywhere ever went off 'on the side' to knock out a prototype as an 'evaluation exercise', now did they?

That said, re the rest of waterfall? Not sure I'm missing that.

I'm not talking block diagrams here. I'm talking about fully fleshing out issues down to the level of functions inputs and outputs(1). So that managers will be pleased with the "planning" and "sizing" and some other buzzwords...

(1) Which (outputs) are another bitter story since we are building on top of legacy code that is working with side effects from head to toes. But let's not touch this can of worms.

Yeah, that's nuts. That's way beyond where even the 'detailed design' phase should go. I've been on projects where DD has delved to the level of identifying individual classes, and I think even that's a bit of a reach. But managers do love their metrics.

Agile got consultancied to death. If you look at all the certification courses and what not that have sprung up around them, barely any reflect the values of the agile manifesto nor teach you how to design processes and organisations with those values in mind.

When most companies say agile, they mean sexy waterfall. That’s not to say that doing waterfall on a monthly cycle doesn’t have benefits over doing it on a yearly cycle. It does and it’s a good starting point. But that doesn’t make it agile.

DevOps has the same problem. To the point that there’s now companies that “do the devops for you” completely missing the point of it all. But at least the company does devops now. We’re back to 90s throw it over the wall and early 2000s outsourcing.

This is a massive problem and nothing new... Kerry Buckley whilst at BT in the UK created this masterpiece that sums it up pretty much spot on -

https://www.halfarsedagilemanifesto.org/

The consultancies also sought to destroy its real meaning.

Now we have the (Product) Empire Strikes Back - sales and product people claiming agile failed and that they should have all the power again by claiming Marty Cagan says so.

No one ever really wanted to let the developers make decisions at higher levels.