I may be a bit too cynical, but there's some element of that in those sponsored hackathons as well.
Then entryist tech companies co-opted the concept to get programmers to work for free on their platforms, and in some cases to even pay money (in the form of an entry or registration fee) for the privilege of doing so.
Sure, they provide pizza and dangle some prizes in front of the participants, but the judging is seldom objective, and the winners are all too often connected in some way to the event sponsor.
It was probably a coincidence, no attempt at co-opting anything.
Not everyone can say they won the Putnam.
Putnams don't count for much anyway; I guarantee you 99% of tech companies are still going to put you through the same demeaning interview process even if you have one, just because they can.