Yup, the login wall is a major PITA. Enforcing that for people who simply want to read the content is a mistake IMO. However, Quora made the decision that it would force enough signups for it to be worth it...not sure I agree, but they have more data available on the issue than I do.
Facebook login required? Forgitaboutit. I've never had a facebook account and never will (sure, I know you maybe can use another service...but just it isn't worth my time).
Quora was started by ex-Facebook CTO / VP Eng, who previously lead "Facebook Platform", i.e. the login requirement now seen at Quora. However, most of the world moved on.
And the UI/UX hasnt been updated for years.Doesnt feel modern.
Just my 2 cents about why i dont use Quora.
Could have been a great tool to build E-Reputation for engineers.