But in any case, you've failed to rebut the "it's optional" argument. None of your examples are related to OP's complaint about using the activity feed to keep up with friends.
Yes. Or are you under the impression that those sites are also not optional?
…except when that website first make you use facebook.
> If your belief that Facebook logins are a bad thing is widespread, people will stop only implementing Facebook logins because it's a bad business decision.
These things are a slow process.
> Stop whining because the market doesn't agree with you.
Luckily, my "whining" (the part about the social logins that you could only argue against, my privacy points were bulletproof and spot-on) is backed up by evidence:
http://www.emarketer.com/Article/Privacy-Concerns-Keep-Users...
Optional like the sites that have "sign in via facebook" and no other option?
Optional in that they track your every move from "like buttons" all over the web?
Or optional that they develop shadow profiles on users that aren't even users?
Which optional is it?