While there may be more jobs in the Bay Area, it's always a battle of compromises when you compare it to another place. For example, somewhere like Boston may have less jobs, but the rent/cost of living isn't as extremely high as it is in somewhere like San Francisco or a lot of places in the Bay Area, which means you can save more money for things like retirement, vacation, etc., and it has easy access to somewhere like NYC, meaning it may be a better fit for the people they interviewed. Friends can always be found where you go, and meet ups can be found in varying degrees, so the main appeal to staying in the Bay Area is mostly going to be job opportunities and networking, both of which are available in other cities like Boston, NYC, and Austin.