I don't really disagree. Although a fair number of people are fine with the Southwest deserts, especially high desert.

But coastal California (which, as you say, is mostly somewhat different from SF specifically) is the only real Mediterranean climate in the US.

This particularly unpleasant spell of weather we had until a couple of days ago notwithstanding, New England generally isn't bad in the summer especially once you get out of the cities. You're rarely going to be too uncomfortable on the Maine coast in the summer even without AC. But, yes, it's cold and snowy in the winter.

Living in San Diego now and by the coast I don’t think it gets too hot (if you can the ocean, it’s likely not too hot). There is usually ocean breeze and most of the year it’s warm, not hot.

I do remember driving up the highway from Mountain View or San Jose many times and seeing this "cap" above SF. Literally going from short sleeves to jacket.