It leaks in that the entire function becomes declarative, and state is colocated to a single function. You don't have multiple jobs for each attempt, passing indexes into each job queue. You don't have to worry about enqueueing each "step" as a separate job.

The code becomes "wait until this time", vs "enqueue this function with this state to run at this time via this message broker, which may enqueue other jobs in ways you can't see".

There's no real silver bullet that will let you run code in the future without specifying "when" that code should run — but workflow engines are by far the more productive of the two.