I doubt Twitter is making deep cuts so they can keep their friends. But it does help to like the people you work with.
Part of being a good software engineer is being tolerable to other software engineers. ;)
I think you misunderstood what I meant, people are less capable technically, but more capable from a "relationship building" standpoint will often spend as much time becoming friends with management so they are not laid off.
This probably doesn't happen in smaller startups, but I've worked in several medium and large size companies and have seen it happen.
It doesn't matter if you're getting along with your coworkers, they aren't the ones making the layoff decisions.
I have seen this exact thing happen in a company I used to work for. It was the catalyst that made me look for another job.
I'm not saying this is the case with Twitter, I don't know anything about Twitter as a company.