God this more than anything before has made me feel old. Is GitHub that strongly associated with open source that alternate models for open source development

God this more than anything before has made me feel old. Is GitHub that strongly associated with open source that alternate models for open source development are a mystery? Somehow that's really troubling to me in terms of the open source paradigm, even though I generally see GitHub as a very positive thing. I don't mean that as a criticism of the poster, just saying that it feels like maybe there's some room for more diversity and competition. I think others have given pretty good descriptions of pre-GitHub models, so I'll leave that to them.