Only if you go on sites that have the ability to receive messages from people (and where those people know who you are). You can choose to go to those sites, or to go elsewhere.
At school, when the bullies are following you around the playground all day long, you've got nowhere to hide.
Also, most cyberbullying typically leaves a papertrail behind it - you can take the Facebook posts or whatever as evidence of what's going on. In the physical world, that's often a lot harder to get.
The point is that the bullying goes from something fairly local (school), that can be escaped, to spreading around the world. This particular kid could move to Cambodia and some people there will probably recognize him.
There's a big difference between cyberbullying - using the internet/mobile phones etc to bully people - and physical bullying that's happened as a result of being recognised from the internet (or from newspapers, TV etc).
At school, when the bullies are following you around the playground all day long, you've got nowhere to hide.
Also, most cyberbullying typically leaves a papertrail behind it - you can take the Facebook posts or whatever as evidence of what's going on. In the physical world, that's often a lot harder to get.