Let's say the user is in FRA, the database in SF. If the "server" is on the edge, you'll end up with 100-200ms between server and database, while the user has less than 10ms latency to the "edge". If the server does multiple round-trips to the database, it can take seconds until the first byte. If the server and database are both in SF, TTFB will probably be less than one second, as round trips between database and server are almost zero. One thing to mention is that it would be beneficial of the TLS handshake could be made on the edge, as it's a multi roundtrip transaction. Ideally, we could combine a server close to the DB with a stateless edge service.
So, the future of the web might not be on the edge. It's rather: The future if the web will leverage the edge.
Or else?