Why does the article say, "It was a watershed moment for Silicon Valley"? WeWork was started in NY, has a bunch of facilities in SF but in SV just one in RWC.
Because Silicon Valley has become a synonym for the American tech scene.
Many great films are made in New York but they still fall under the moniker Hollywood.
Its not a technology company either though.
I think you're underlining OP's point? WeWork is head-quartered in NYC but does some biz around the world and is called SV. Hollywood is the location of many of the headquarters of movie studios, though they do work around the world.