I regularly spawn several thousands of threads in the C++ servers I write, and they perform well. At least 40% of FAANG companies just reduce the size of their per-thread stacks. "Thread per-connection" works just fine, and when you need to go faster, thread pools work even better without coloring all your functions.
There is an extremely small set of domains where simple threading doesn't suffice, and async/await is too high a price to pay across the entire software ecosystem just to slightly optimize those domains.
There is an extremely small set of domains where simple threading doesn't suffice, and async/await is too high a price to pay across the entire software ecosystem just to slightly optimize those domains.