It can be a good use case, to increase the number of concurrent users you can serve. See my comment elsewhere in this thread.

You should still be able to output an ID when using async/await. It just means that the calling thread can do something else while it waits for the DB to get back to it. Execution will resume in the same place.

As mentioned elsewhere in this thread, for a distributed system you can use GUIDs to remove a immediate dependency on the DB. You can adopt eventual consistency and merge later, but this adds lots of complexity. If you do go down this route, add the GUIDs as an additional key and stick with something sequential for PKs, to avoid clustering issues.