More like "forces seeking to block development lend their backing to environmentalists because they realize that they share some common ground" but I agree that the blanket characterization of environmentalism is an exaggeration.

A lot of local governments were overtaken by the anti-growth environmental crowd at the time. Marin County in particular had their 1968 growth plan revoked and a famously anti-growth plan replaced it in 1971:

http://www.sausalitohistoricalsociety.com/new-blog/2018/3/7/...

'The decisive blow against growth was initiated in 1971 with the issuance of a Marin Planning Department report that proposed preserving Marin's lands except along the Highway 101 corridor. Entitled "Can the Last Place Last?" the report took its theme from Lew Welch's 1969 poem "The Song Mt. Tamalpais Sings" The poem lamented the "hordes" that were "now piling up" and contained a refrain that captured perfectly the sentiment in Marin: "This is the last place. There is nowhere else to go."'

The city of Bolinas is notorious for vandalizing signs that point to it, to ensure outsiders can't find their way there. And they have a Bolinas Border Patrol, in a "ha, ha, only serious" kind of xenophobic way.

https://www.belle-aurore.com/mike/2013/05/bolinas-vigilante-...

yes, marin is a bastion of nimbyism (it's also quite pretty) but that's not the "entire environmental movement". the objection is to the exaggeration.

Fair, sorry for my histrionic wording. The "roots of the environmental movement" is more like what I'm getting at. Put it this way: I care about the environment more than ever but no longer consider myself an Environmentalist™ after learning more of its history :)

no worries, labels like "environmentalist" don't matter nearly as much as intent and action.