Eh, don't know what's going on with you. I've never had to give Google any phone number. They do offer password recovery by text and two-factor authentication by phone, but both of those things are optional
I don't know either, I heard from someone else he was able to create and link accounts without giving a number. But I did a quick search and found other people are having the same issue as me. When I try to create the account I get redirected to this screen, the verification for my account:
http://i298.photobucket.com/albums/mm270/Aiylah/damngoogle.jpg
It's the same whether I try to create an account via the Youtube prompt or whether I go straight to Google accounts and make one there.
Edit: In their FAQ, they say "In an effort to protect our users from abuse, we sometimes ask users to verify their identity before they're able to create or sign into accounts." and "If you're trying to sign up for a Google Account, you may be asked to provide a phone number to verify your account."
Guess I might just be one of those unlucky people. Wonder if I can try creating an account from a different computer or something.