Earlier quoted context omitted.
PoS was known way before PoW. It simply doesn't solve the problem at hand - decentralized consensus between mutually distrusting parties.
IOHK has many conference accepted peer reviewed research papers that show that proof of stake has equivalent security properties as proof of work.
Only if we enumerate all possible attack vectors, and prove resiliency against these, is the proof as general as you claim. The difficult part — as the WPA2 paper shows — is the former.
How do you know when you’ve enumerated all possible attack vectors?