I don't agree with this entirely, although I know what you are getting at.
Its quite possible its just an age thing. Younger people are more likely to be new to the Internet these days, and probably use a name with numbers just because its so common to have a number based nickname online. And of course a new Internet user (and one thats new to Blockland) will probably not be familiar with Blocklands general etiquette, or even that of the online world.
This is just one theory, you could explain it in many ways. Or maybe its just people with numbers in their names are assumed to be less intelligent because of this generalization. You have to admit, when you see someone with mario or halo in their name you automatically assume they are going to be really immature. And some of us won't let them prove otherwise.