Basically here is the concern, in a multi tenant environment, users could step on each others toes because the libraries are currently shared across everyone.
A simple example:
user1 - creates library math
user2- also creates a library math after user 1, currently user2's library math will override user1's library. User1's functions could no longer even exist, or maybe user2's library uses the same function name as user1 but the method itself does different things. Now user1 may not know their function is now doing something else.
Should users be interacting with a shared set of libraries or should libraries be specific to each user in a multi tenant environment? I would think each user would expect to have their own set of libraries