What if DP setting is: You must log-in in order to read the thread. Will DP become less popular? I do see many famous forums must login before to read. Do these kind of forums get less index by G? If they get less indexed how do they still have so many members as fans?
yes, if you have to login before you read the forum / thread then that means that Google is prohibited from indexing that part. A lot of forums do this to prevent server costs running wild