I grant that there's no one right way. There are many, and they depend on circumstances. I certainly grant that there are an ocean of idiots selling bullshit. But you're throwing the baby out with the bathwater.
There are better and worse ways to make software. Teams can reflect on how they work and get better over time. Those teams can recognize patterns, and other teams can benefit from learning about those patterns and trying them out in their environment. And that's how things like Extreme Programming came to be: teams experimenting and sharing what they'd learned with other people who wanted to get better. That was exactly what the early Agile movement was.
Piss all over that if you like. But you'll be missing out.