This reminded me MIT still uses ~<email> for public www space. Must be an artifact of this UNIX paradigm. Brian Chan as an example: http://www.mit.edu/~chosetec/.
It's Apache's default UserDir module that does that. It's only the request-controller model of dynamic web application development that has made it look unusual compared to something like /user?id=moemaya or /users/moemaya or whatever.