I do think that "Agile" is to blame. In my view the Agile software methodology is like Communism or libertarianism. Whenever you point out the myriad ways that it can fail in practice, someone always jumps out to say, "Well, what you're not describing is not true Agile. True Agile has never been tried!"
This is a great point. If there's a tool that no one can figure out how to use properly or effectively, it's hard to argue that the tool is well designed.
You could say the same about vim though...
Jokes aside, many resources about agile start with explaining how agile is “easy to understand, difficult to master”, and I think that’s true.
The difference is that vim is a specific tool, and if I see someone struggling repeatedly to be effective with vim, I can gently suggest that they try some other tool. But if I see a team repeatedly to implement something that looks like an Agile methodology, what do I tell them?
I suspect that many devotees of agile would speak at this point about getting management buy-in, or reforming the wider organization, but at this point "agile" just becomes shorthand for "reform your entire organization from top to bottom so that your management doesn't suck".
If the team struggles, the org does not need to be changed. However, from my point of view, companies should increase support for their teams when transitioning to agile. Training would be a good start. I have taken a few agile trainings, and they have been among the best I had in my career.