Of course many individual teams fail at agile but those teams would probably fail no matter what approach they were using.
That an emphasis on delivering software, on interactions instead of process, etc. seems normal and no different permeates the industry such that people see it as the status quo. I assure you, that is not how it used to be, and there is a huge difference other than less emphasis on documents.
The major innovation of Agile was that you acknowledged that the various steps of the Waterfall/Spiral happen at the same time - in the Spiral days, that was considered something to be embarrassed about.
I don't doubt, by the way, that you were taught that the Spiral Model was called Waterfall. But you should be aware that this was a case of historical revisionism on the part of whomever taught you.
I also remember being taught that errors caught after the software had been implemented was 100% more costly to fix than errors at the design stage - I think that was the idea behind big(ger) design up front.
It is basically true for waterfall because the feedback loops are broken. Think cooking, for example: if I cook all my meals for a year at once and put them in the freezer, I'll have to do a lot of research and planning. Otherwise, a single mistake could lead to me throwing out up to 1000 meals.
But if I just cook every meal as I go, I can tinker quite a bit, because the cost of failure is limited to one meal. Which is no problem; if I really screw up, I just pull the frozen pizza out of the fridge.
Extreme Programming in particular can be looked at as a set of methods to flatten the cost of change curve. Then if you add the Lean Startup approach on top of that, you end up testing your core hypotheses early on, so even major shifts in business direction end up being pretty inexpensive.
It works fine for us, but we have the ideal conditions for it to - business product owners who understand that their role is to provide a prioritised backlog and clarify stories in a timely manner - and nothing else. We have an organisation that accepts that the developers will drop features from a sprint to safeguard reliability and quality. We have teams that have stable core domains so that our estimations are, for the great majority, sufficiently accurate within that core domain.
Every time I see a "Agile is a scam / it's dead Jim / it's a myth" post, it usually involves into someone doing something dysfunctional and then trying to justify it with "But Agile!" in a game of Buzzword Bingo.
I went to help a local government IT department that was trying to implement Scrum to get some clarity on what the hell was going on in their dev teams, and I sat in on sprint retrospectives where all the talking was done by the 'product owner' - who was actually a rebranded business analyst who had no authority to prioritise backlogs. He wouldn't stop talking either, even when I explained to him that the retro was for the team, not him.
To that team, Scrum was a bunch of bullshit. To me, how they were doing it was obviously flawed. That said though, ultimately, that organisation has derived value from their half-assed implementation of it. It's shown them precisely who contributes in their IT team and who is cruising. They've got a few people who claim a monopoly on certain areas and jealously defend them because it makes them feel necessary and as such, safe from being laid off. Hence I had a GIS guy telling me that "You can't expect .NET developers to learn GIS!!" and an ABAP developer saying the exact same thing.
Now that organisation faces the challenge of managing the coasters out - unlike the US of A we don't have at-will employment.