It probably implies that only certain types of start ups are well suited there. E.g well funded VC startups that are looking to go big or go bust where paying lots for talent is worth if for access to many more employees and VCs.
I'm talking about startups that are outside the Bay Area, and outside the US.
On-site-only is a lot more productive, we just like to pretend otherwise because we wish it wasn't?
As evidenced by?
I'm offering it as a possible explanation for why onsite-only Bay Area startups could be a success but remote startups not be able to afford Bay Area salaries.