They frequently seem so obvious after-the-fact, like "how did we miss this?" Like, here, stated in just a few pages, is an idea that so many smart people have been chasing after for years. And it's presented so well that it seems intuitive, when in reality it was a very difficult challenge.
If anyone is wondering, the answer is that the academics had blinders on in their search for a cryptographic solution to the problem of decentralized transaction ordering, an impossible thing. Satoshi's solution is to accept that impossibility and use economic incentives to achieve eventual consensus instead, and it turns out eventual consensus is good enough.
There was also some work on hashcash money, but it made the economically naive and inaccurate assumption that value of the currency must be linked to the cost of production, which is also explicitly not the case in bitcoin.
Reality check: nothing conclusive has been proven yet.
IFF we get to the VISA network level of activity, then it has "turned out" to be "good enough".