4 accounts? That's still rather generous given how many storage you get with a Gmail account
But where does that observation come from?
I find it odd that there is no specific number specified by Gmail, because how do they determine what is "too many accounts"? If they don't have real criteria set for this, on what basis will they judge?
If only it were possible to sign up for a Google account using another email address (eg a Yahoo or Outlook address that you could use for creating a Google account to post or comment on YouTube etc) then I'd probably do that.