I don't think that's accurate at all. Startups are just a small subset of companies that require office space. On top of that startups looking for office space are an even smaller subset, and those who have founders or employees lurking on HN an additional step down the funnel. People who "want" to start a startup are even further removed from requiring office space. This is rounding error stuff.
The reason the companies I mentioned have actual and natural 'hn marketshare' isn't because they're b2c vs b2b (which is incorrect anyway), it's because they actually do provide tools, services, platforms etc that HN users in enormous numbers need/want/use.