My tech employee friends in NYC, who work for respected names and are great at what they do, don't spend weekends at hackathons or weeknights running from tech office to tech office for free food at meetups. Here, it is okay and even normal to finish a work day and go experience art, culture, history, etc... things which all do exist in SF and are often great quality there, for sure, but which in certain employment circles seem to be pretty much ignored.
To each their own.
Outside of SV startups, many companies in the Bay have reasonable hours. There is definitely a workaholic expectation in NYC.
It's a perfectly diverse metropolitan area with tech as an addition, not as a replacement. That's strictly more than many other cities I've spent time in from Ottawa to Charlotte. Calling it a monoculture is simply not accurate or, if it is, so many cities don't have even that.
There exists things that aren't tech in SF, but the scale of which is much lower than other major cities like NYC. More importantly though, even in non-tech scenes, tech is always there. It's the guy at the party that seems to find you no matter how much you move around the room. I found it suffocating - no matter where you go you can never fully disengage from the industry.
The measure of a tech monoculture isn't (IMO) the existence of other things, it's whether or not tech tags along with all of these other things.
The monoculture of "tech" is a grind after you visit other places. The Bay Area is a fine place if you get excited by networking events and like asking people at a bar about their deck, but I find it mind-numbing.