Joni was on the edge of fame and was scheduled to appear on the Dick Cavett show at the same time as Woodstock so she was advised to skip the concert and appear on television for the national exposure.
I don't know that the song would have happened at all if she'd been there. Nobody else that I can recall wrote a song about being there, at least not that I can remember. It certainly wouldn't have been the
same song, or likely anywhere near as good.
If you think about her haunting, haunted version on
Ladies of the Canyon, it's more about longing than any kind of memory, fictitious or otherwise. The most powerful lines, the fulcrum on which the while song rests, are "we are stardust, billion year old carbon, and we've got to get ourselves back to the garden." Not a literal garden. Certainly not Woodstock or music festivals in general. Metaphorically, it's Eden. In practice, it's about transcendence to a state of innocence that neither she nor anyone in her audience had actually yet experienced.
It's the "not having experienced it" aspect that's at the core of the song. The rest -- the child of God, Yazgur's farm, songs and celebrations -- is just how she's telling the story.
In the scheme of things, Woodstock as it happened for the 250,000+ people in the ground (the "half a million" figure is pure poetry; even the hype-iest of the organizers never claimed anything close to that) was never the point. It's nowhere near the biggest festival ever, and I would argue that, musically, it wasn't even the most compelling festival in the summer of '69. The vastly larger impact was from the MOVIE, especially the re-release following its Oscar win in April 1971. It legitimized youth culture as more than garbage merch and attempts to recapture The Beatles' appeal to tweens and younger (NOT teens), and it told those of us in the hinterlands that there were more of us than we'd ever imagined.
Imagination was the thing. Imagine being there! Imagine so many of us! The song Woodstock, and almost everything about it, grew because of what we saw, yes, but also because of what those sights inspired as visions, a combination of nostalgia for something that never happened but might have, and for a future that seemed impossible, but
might be possible.
So it's not
ironic that someone who wasn't there wrote the ultimate ode. It's inevitable. It's essential to that version of the song, because
that version is about longing.