Problem was already solved: "In modern times, the vast majority of UNIX systems have evolved, and now the kernel ensures (more or less) only one process/thread is woken up on a connection event."

I believe that quote from [2] is referring to simply calling accept(), but modern socket servers use epoll() (or similar) before accept() which I think still has the problem (because I've run strace on nginx and uwsgi and I'm pretty sure I saw all processes wake-up from epoll()). So I'm thinking that with SO_REUSEPORT, each server process would have a different socket to epoll() on, and the kernel would only wake-up one process on a new connection, thus, solving the thundering herd problem for modern servers.