The number of users reporting regular use doesn't necessarily mean more people are using
I feel much more comfortable talking about useage now that it's legal & more socially accepted, but legality did not influence the frequency of useage for me or the friends i knew who smoke weed
So first: most jobs require you to do a lot of stuff that you may not agree with or feel is useful. I don't want to work with the person who is going to only do what they want when they want. At the end of the day the work needs to get done.
Secondly: any school that has GPA is essentially holding a contest. Many job postings consider GPA and may use it as a tiebreaker between 2 canidates from school X. It's not a perfect metric by any means, but it is relevant in the world today for new hires.
Work in the real world is largely the ability to deliver on expectations.
The reality is that you should be learning how to prove, not memorizing proofs.
The student who was most prepared would be able to derive proofs (by the process that was taught, like knowing to apply a theorom, or being comforatable with induction, etc) in a timely manner.
The exam is there to see how well you grasp the material taught, not how good at winging it you are (which is a very useful skill of course, but not the one being tested)