The executor_work_guard is required for situations in which the IoExecutor (Executor associated with an IoObject) has different identity (or type) than the Executor associated with the CompletionHandler (e.g. when used with asio::use_future_t). Since this is not a "primitive" async operation (that calls directly into the OS and manages operation suspension), we don't need to maintain an executor_work_guard for the CompletionHandler's executor. Currently, the IoExecutor is always io_context::executor_type, however there is a proposal (https://wg21.link/p1322r0) to enable users to provide custom Executors to IoObjects.