Initially, you're right. What you're pointing at is: Accepting the responsibility brought by your own actions. (in short)
You're forgetting one minor thing; your concept works when you break it down to an individual. When you talk about masses though, you'll need something that's considered governance, rules, regulations, security and enforcement.
Human nature throws caution overboard when we see many others running in one direction (myspace, online dating, etc) and we follow without asking many questions.
Call it a mental avalanche or now recoined, "viral" - it starts out with one snowflake and it ends up becoming a mass movement. Myspace is exactly that. Social Networking is just a more hip term for all this.
Once someone creates a conduit to facilitate this viral social experience, they also accept the responsibility to govern, regulate and secure the environment they've created. This is where myspace, facebook and whatever else platform there's out there, fail miserably.
They've fallen victim to human nature to follow the herd, it snowballed out of control and they're incapable of securing the environment, UNLESS they'd be willing to sacrifice a lot of subscribers. Only problem with sacrificing subscribers: It means less page impressions, a smaller target group, and ultimately, less advertising revenue - in the big picture. No executive in their right mind is going to deliberately inhibit their opportunities to make a profit, mass movements, tainted security, and a minor percentage that's endangered are a small trade off to looking good in the boardroom.
Before i completely go over board though, think past the individual and look at the responsibility that a company should accept by providing the arena for what can spin out of control.
The meeting someone on the internet for sex thing is more common than you think. I dont know if you have heard of "Dateline NBC", but they set these things up where they chat will people through myspace and chat rooms. They arrange a meeting with the person at the "decoy's" house. The "offender" shows up and tell the girl or boy that they want to have sex and other things with them. These are guys in the ages of 20-60 yrs old that show up to do things with 12-17 yr old girls/boys. Its not about being stupid, its the ignorace of a child that comes in to play in these situations.
A parent can say not to have a myspace and regulate that at home but whats stopping them at school and friends houses? There is more responsibility on these companies than anyone cares to think about. Plus you know that every 16 yr old girl wants to date that hot 20 yr old. They dont think of the 45 yr old man watching her profile.
Not everyone is the same when it comes to themselves. Some people have been bullied their whole lives and have very very low self-esteem. This constitutes directly to suicide.
