Yes. I think I don't understand something, because without a cohesive concurrency story, it isn't clear how you're supposed to glue different components together effectively.

For example, an http server is using nonblocking calls and dispatches to its own threadpool. The lack of cohesiveness means that the blocking call made by the PostgreSQL library can't feedback into the http server's concurrency model. The http server could expose or pass some control mechanism into the application, but for that to work, all the libraries would need to support it.

A lot of people don't seem to think this is necessary, and I've generally assumed that they're right and there's stuff I just don't understand.