I was dating people nonmonogamously before I learned about EA, and before I moved to the SF Bay Area, but it’s much more of a default relationship style in my community here. The main effects of this seem to be (1) it’s easy to find partners who are open to polyamory, (2) there are fewer norms against flirting with people you know to be in relationships, (3) there are lots of people in the community with casually romantic or sexual connections to each other. This doesn’t seem clearly good or bad to me.
I do think the normalisation of polyamory, combined with the strong gender skew, means that young women who move here often receive a lot of immediate sexual/romantic attention, and going on dates with people is definitely a way to immediately grow your social network (and, thus, your professional network). This is… okay, I guess, but I dislike that the default social role for new young women arriving in the community is “love interest”.
From a woman in the SF Bay Area: