As pointed out in the article, not using the SDK does not preclude authenticating with a Facebook account. It just requires a bit more work on your end to protect your non-Facebook users.
"Don't use" and "only use for people who actively opt-in" are two separate things, so no it doesn't come down to what you care about.
I'm saying give people choice, let them figure out what they care about. Making the choice for them is bad business and bad ethics. You don't know better than your users.
Non-Facebook users are unable to opt out of Facebook tracking if you use the Facebook sdk. That’s the point of using the oauth standard, it allows those users a choice not available with the sdk.
A little bit of research indicates that this is still a non-trivial amount of work from the developer; that the developer has to make the choice to protect the privacy of their non-Facebook users by dynamically loading the Facebook SDK.
The problem is practical; do your users want the features or do they care about privacy? Let them make the choice, and don't hide it from them. That's the ethical behavior.
It's unethical to assume everyone values everything the same, including privacy. Some people don't care about it as much as you do, nor should they.
There's no ethical argument for depriving someone of food but people fast all the time. Further, the war crimes my gym trainer is guilty of know no bounds!
You can give up your "human rights" for convenience/pleasure as long as you can reassert them down the line.
Fasting and training are both conscious deliberate choices - how will you frame the loss of privacy in such a manner that it can be agreed to with the same degree of intention? Most people have no idea and don't understand - if you wanna go with the "opt in" solution, you're going to have to make a compelling argument that the people making the decisions are educated enough to make them.
Given a hospital patient who doesn’t value taking care of their health, should it be ok to administer X-rays without concern for radiation exposure? If the patient doesn’t care, is it ok then?
Given a person who doesn't like their nose, should it be okay to provide cosmetic surgery to that person, despite the risks any surgery comes with? If the patient doesn't care, is it ok then?
Given a person who wants to jump out of a plane, should it be okay to let them, even though it's a relatively high-risk activity? If the jumper doesn't care, is it ok then?
Given a person who wants to run for national public office, should it be okay for them to release their prior year tax returns, even though it's an exposure of their privacy? If the candidate doesn't care, is it ok then?
Turns out, this isn't an easy game to play, so stop trying to decide for others what they want for themselves. You don't know their situation.
They’ll tolerate a lot if you’re providing enough value. They’ll even tolerate giving you their money if that value is high enough so why wouldn’t they tolerate having to not use a social login?
So it does come down to what you care about.