The problem is not that they couldn't, but they wouldn't. Most of the large bay area companies believe that there is more value in the chit-chat and overheard conversations at the micro kitchen, than in solving the remote work problems.
Most of my work is remote and yet I agree with this. It's part of the reason I visit the office at least once a week, despite a 2-hour commute. There is value in casual conversation. Work topics can be raised in informal ways. People share more of their personal lives and come to know each other better, fostering understanding and relieving some of the tension that can arise from misunderstood or poorly-worded emails.
Working remotely requires a lot of attention to relationships in ways and over channels that most people aren't accustomed to. It can be difficult even for people who are very good at it. I enjoy working remotely but I value the personal face-to-face time I get with co-workers very highly.
