I think this is the key point. Voluntary prior art hunts have been a successful strategy for defeating stupid patents[1] for many years now. There may be arguments in favor of bounties for more obscure or less stupid patents, but when the collective demand to fix this problem is so high, the price point is rather low.

[1] "Stupid patents" is a technical term here -- or it has been since Mark Cuban funded an EFF staffer to challenge bad patents on the condition that the position was titled the "Mark Cuban Chair to Eliminate Stupid Patents".

https://www.eff.org/press/releases/staff-attorney-daniel-naz...