I’m really, really starting to hate seeing this when I download a new application:

My objections:

• What if I stop using the service I choose to log in to your application?
• You are totally going to spam my friends and followers on the service I choose—likely without asking me.
• I use different strong passwords for as many applications as is feasible to limit the surface area of any personal security compromise. You’re not letting me control my own security.

What I think when I see this:

• You were too lazy to write your own login and authentication system.