We don't, really. I certainly grew up without them. It did both good and bad things. It did centralize and simplify some things, but that came at a cost of freedom for more power users. It was great for sorting out dependencies at a time games were still often bad at doing that cleanly on their own for less-technical people. I think it did good things for community, though, particularly for those of us who did not use any modern consoles that had various party/SNS-like features baked in.