Remove option "Just a username, please." at sign-up

Hello,

I’d be grateful if you would share with me how I may remove the option to create just a user name at sign-up.

I don’t see the need to have users that don’t have a website.

Am I missing something as to why this is an available option?

Is this important for any reason?

Is it because registered user can comment or join the support forum?

If so I don’t want user without a website.

Thanks in advance,

Ralf