Imagine for a second, you're an average user. A friend sends you a link to this website.
You click the link, see some text near the bottom of the screen. As you go to scroll to read the consent, a button appears out of nowhere and all of a sudden this website has your personal email account information.
The site auto assigns you a username, and you're logged in automatically.
You freak out a bit. You never wanted the account, you didn't want to be authenicated, but whatever, its just an account. Logout, exit the site, and continue on with life.
A couple weeks later, that same friend sends another link, and you click on it.
This time, you're automatically authenicated using that same account they created for you automatically, against your consent.
The question is why?
The answer is obvious, manipulation of user registration stats to bump their numbers.
Reddit is a malicious site, they need to be blacklisted from Google due to their intent to clickjack users into creating accounts