It's not snake oil because it's new. But because of the blatant lies (and occasionally more subtle distortions) in the developer's project proposal, staring everyone right in the face.
Nor is all new development bad, nor old development ipso facto good, by any stretch. We get the issues, and understand the tradeoffs.
And I, at least, don't demonize YIMBYists. I just wish they'd stop being so smug, and find a better way of supporting their position than simply responding to any expression of opposing viewpoint with facile generalizations and tired caricatures.