Discontent with social networking sites

There is one aspect of social networking that I'm frustrated with. It is that people always add other people to their "friends list" (or whatever that particular platform calls it) when they don't even know who they are actually adding. On a regular basis, I look at people's listing and see that they have a large number (in the thousands) of friends. I don't even know how it's possible to keep up with that many "friends". Personally, I only want to add people that I care about and that can help me succeed. I believe that adding only people you know will increase the amount of "relational experience", and minimize the amount of "comment spam" and other random things that you are probably better off without. Recently, I have ventured into the contact management arena with sites such as 37 signal's Highrise. This is due to my lack of faith in social networking sites. CRM (customer relationship management), or "contact management" sites are helpful because they provide a user space for each person, instead of just a generic "guest book" type framework found on most social networking sites.What are your thoughts on this? Do you think adding people randomly is good for your "networking"?