It's an unwritten rule! A type of common courtesy. When you drop the ball,you get" called out" by your peers in a good way. You have to register and or pay to gain
access to the information, it's best to provide knowledge when it's free to access,like a library.
It's easy for me cuz I get logged in automatically and some time forget like being a member of IEEE.
Or other institutions Massachusetts institute of technology, California institute of technology, National Institute of Standards technology , so on and so forth.