[contactmatts]

If someone is _solely_ working at company because their friends work there, it can be a fragile engagement. What if one or more of their friends leave, or worse, are fired?

(Notice the emphasis on solely; obviously having your friends working at a company is a plus, but should not be your complete basis for working somewhere)

[Fuxy]

Of course it's fragile attachment to friends and family in a company can be more motivating then any speech a founder can give.

You are a lot more motivated to give it your all when you know a friend or family member is relying on you then some random strangers you happen to work with.

You can't have a united, motivated team that you can chop up however you like without consequences.

[loumf]

I think the author is pointing out that an applicant is more likely to believe that a job is interesting and a company is good to work for if their friend works there and is recommending it. So, those other things are taken into account, but the interviewer's view of them isn't necessarily important to the applicant.