Is there anything special to this experience? Historically, all kinds of delusions were "widely shared". This is true even today. People "talked" to trees everywhere around the world.
Yes, it is plausible, but logically impossible.
Under influence people think peeing in public is OK is plausible, though logically it is not the best action to take. So that is not unique either.
> The paradox is that by talking about the Tao, and by attempting to define the Tao, we ensure that the reader does not actually grasp the concept. At its heart, the Tao is nonverbal in its essence, beyond the confines of language. The Tao is an experience rather than definition.
Each tradition has their own version. For the west, it's the coincidentia oppositorum of Nicholas of Cusa. This goes beyond definitions because language can't describe it. This is not a failing, this is the essence of its impossibility.
https://en.wikipedia.org/wiki/Nondualism
It's considered an "ultimate truth" in those traditions. The question isn't whether or not this is delusional, it's why is this experience widely shared across human history.