Once you have an async API (of any kind), and have paid the cognitive and technical price of having one, you have a lot of flexibility about what you do on the

Once you have an async API (of any kind), and have paid the cognitive and technical price of having one, you have a lot of flexibility about what you do on the implementation side - including thousands of threads. If you start off with a synchronous API and thousands of threads, migrating to something else later is very expensive.