The manifesto is concise, but I wouldn’t call it clear. I think that’s why “agility coaches” have their niche.

You can’t really teach beliefs, which is why it’s formatted like an agreement. Everyone is supposed to at least think they share these ideals, and make choices that align with those beliefs. But that’s much too introspective to be marketable as meta-work, so people have started reading between the lines to explain away specific meetings or processes. Because “agile” as a concept is so unclear, it’s easy to expand on, creating the weird Frankenstein situation you’re talking about.