Facebook has an algorithm that determines when friend requests look unnatural. If you cross a certain line, Facebook will block you from sending any new friend requests for 30 days. The types of activities that can get you blocked include lots of friend requests that have gone unanswered, or (worse yet) marked as unwelcomed.
There is a lot of chatter on forums that getting a “this answer is helpful” votes on an answer you post in the Facebook Help Community Forum will help you get unlocked. Facebook, however, has repeatedly denied this. Just for the record, you can get to the Community Forum by clicking on the gear icon to go to your settings. Then choose Help, and look for Community Forum.
If you want to get Facebook updates from people you don’t know personally, you can choose to follow them, instead of sending a friend request. As a “follower” you will get all their updates which have been coded as “public.”
By the way, I do not accept friend requests from people I don’t know in real life, and I have pretty stringent definition of “in real life.” But I am aware that I have followers, and try to post a good mix of public updates. You can follow me on Facebook here.