So according to people voting with their feet: no, San Francisco was not a brilliant place before tech. Or at least it wasn't brilliant enough to attract a net increase in population.
But so was San Jose. Apparently the "downtown" was boarded up in many places till the late 90s when it began emerging from a mini-Detroit like state. MacEnary was feverishly trying to resuscitate it, I don't think it was his effort so much as it was tech to the rescue, else it would have been an Albukerke.
In SF in the 1980s, SOMA was one of the cheapest places even in a cheap city like SF... lost of broke creative types living in old warehouse/industrial space that would otherwise be going derelict.
In lower Manhattan whole neighborhoods were in a similar state -- bohemian artists occupying loads of space that nobody else would touch.
And in London plenty of neighborhoods were full of squats. Housing stock had become so worthless that it wasn't even worth the effort to prevent people living there for free.
Now those same neighborhoods are among the most expensive urban areas in the English-speaking world. People are literally spending millions of dollars to live at those exact same street addresses... in some cases even living in the same structures, just instead of a half-derelict warehouse it'll now be all marble countertops and the like.
All of these places have their own stories and unique factors, but it's also very remarkable how similar the trajectories and how extreme the swing has been.
https://www.nytimes.com/2001/07/24/business/a-city-takes-a-b...
Here’s some enjoyable reading for those with a few minutes to spare: http://www.sfmuseum.org/hist1/early.html
To me the confluence of cultures, like the brackish waters of the bay, are it’s hallmark. The issues around sudden wealth, excess, limited housing, and visionary governance seem to be more about the place than a particular moment.