that in the absence of RCV, most people would've just voted for their number 1 choice (which may be flawed but I haven't seen anything to indicate otherwise). If so, wouldn't Adams just have won by 10 percent?

I think the larger story here (and unpopular opinion) is that outside of progressive enclaves (and social media), there's still some skepticism of some of the policies and practices of those farther to the left.