> I mean you can die on that hill, but I'd hazard a guess that nearly everyone considers SF a part of Silicon Valley
Well, unless you're from the SF Bay Area (or just Bay Area). SF is a city. SF Bay Area (or just Bay Area) is a broad region. Silicon Valley is San Jose, Sunnyvale, Santa Clara, Redwood City, Mountain View, Palo Alto, Menlo Park, and Cupertino.
Also: https://duckduckgo.com/?t=ffab&q=SF+vs+silicon+valley&ia=web
For anyone in the Bay Area, Silicon Valley is some ways south of San Francisco.
That said, a lot of startups are in SF, because Silicon Valley is too expensive (though SF itself is catching up because of the second dot com boom/bubble), so it's not surprising that outsiders lump the two of them together as a hub of Bay Area tech activity (which they are.. but they're just two distinct geographical areas).
Secondly: Not to say that Twitter, or other tech firms, don't have a bunch of people who are not very productive/contributing - but is this a problem unique to tech companies and not every other company that grows beyond a point?
Are pharma companies, car manufacturers, utilities, CPG, etc etc all running a perfectly well oiled machinery. Or, is it just that the people who have been on the outside looking in with jealousy suddenly get to vent their rage during times of such correction since it gets them eyeballs.