And I entirely disagree that programming code /requires/ any social interaction at all. You can do it purely alone in a basement with no contact with anyone.
Even if you're making your own product, you at least want to get market data and/or customer feedback once you release it. Otherwise, what's the point of selling a product if your customers don't like it?
And I'm not saying that gathering requirements is Mozilla's only social development. I'm saying that you underestimate how much social involvement there is to development, especially on the organization level, where code isn't purely technical.
Because I think that is a core distinction many of the commenters are concerned about here.
If you don't want people telling you what to do, Hacker News ain't a great place to be.
For example, if you were trying to construct an app to measure diversity, you would need to know what category to measure, how to measure it, how to present it, etc.
And getting requirements right is paramount to the results of the code.
Of course, there are projects where these discussions are probably minimal (such as a kernel for instance), but in most cases, it compromises the majority of software development.