Yes, I think using FB login pretty much solves the problem as it is today. Take a look at civilbeat.com a regional news site by Pierre Omidyar (The Intercept). I'm fairly certain they only allowed comments via FB login for years. It meant a lot fewer comments than they would have gotten but they were all legit. Now it looks like they allow FB, Twitter, or local auth. But the comments are still mostly ok. Maybe they are looking for more activity by easing the requirements and believe they've built a culture of good commenting?