I think Tom is right that MySpace lost out to facebook because it is underpoliced. It became the cesspool of the internet. Policing can take many forms, for instance, Facebook doesn't allow people to add a lot of "bling" to their profiles as MySpace does/did. Reddit and Slashdot crowdsource their policing, by having a rating/karma system that discourages people from posting stuff that is bothersome to others. There are all kinds of things that can be done.
But just letting anyone do anything is not a good approach. The small minority who will get up in arms about such a thing is nothing compared to the masses that will leave when they decide that the anything goes approach has allowed G+ to become a cesspool like MySpace.
In my opinion, Facebook was better not because of it's policing, but because it had a better UI and lacked the hideous looking profile themes of MySpace.
But just letting anyone do anything is not a good approach. The small minority who will get up in arms about such a thing is nothing compared to the masses that will leave when they decide that the anything goes approach has allowed G+ to become a cesspool like MySpace.