The progression of social quality on the net is much like the progression of networking sites, even if social quality fell to pieces long before network sites showed up.
My first networking site was LJ, which is just a community blogging site, and blogging an extension of networking. I still don't have a problem as much with LJ/blogs. There is plenty of meaningless banter and clucking, but there is actually people talking, thinking and sharing. Friendster hit, and it was a little successful, but only seemingly with certain groups. Then comes along myspace, and it is exactly like friendster but with poorer coding and systems that fail all the time. Yet, it catches on, seemingly for being able to spam pictures and geocities-esque page designs and glitter. The website still retains some social commuication, with a journal/blog area and page comments.
Following myspace, was facebook, which had been mostly college networking but had opened up beyond that. Gone completely now are blogging and social communication, and in replace are the pictures and 'apps'. App spamming beats out picture spamming. And comment spamming is easier than ever.
Now we have twitter, which is like the internet for dumb celebs. With its word limit, the banter remains but it might as well be grunting and slapping. Despite facebook's near void of social communication, twitter manages to go even lower while being text based. Twitter actually returns communication to pre-language days. (Which, honestly I see in a lot of public social interaction)
So social networks become more shallow and less intimate. Which is part of a greater social trend towards the downfall of human communication. Too may people are full of talk without ever saying anything. It sounds like a bunch of noise for the sake of noise, sound for fear of silence. A bunch of jive and catchphrase.