Earlier quoted context omitted.
I've belonged to numerous teams that followed some form of agile, to varying degrees of success (or failure). The shape of what Agile meant in each of those teams was very different from one another. It would be disingenuous to say "the ones that succeeded were truer to Agile". If Agile can be summarized as "employ tighter feedback loops", the whole Agile thing was beyond useless. A single sentence, as useful a tenet…
Useless as it might seem, I really do think it is actually that basic. Is it useless? Hardly. Take out feedback loops and see what happens.
And if this tenet is all Agile is, then it contained zero new ideas or contributions.