So you are okay with the fact that anybody who knows your email address could lock your account by entering 5 random passwords in a login box?
Well, other services have that system and no one has locked me out of those. Plus all you need to do is hit reset password, then you get an email to your email account which can be on your phone, tablet, computer and then reset your password.
You do realise banks lock you out after 2 wrong attempts right? Well mine does. Although I don't use my email to log into that.