> Almost everything there

Everything. But the mere presence of "equivalents" doesn't make pure functional programming less valuable.

My view has been that reinventing imperative programming (IO monad) on math (pure FP) on imperative programming (the machine) brings me no benefit.

What does a coarse-grained effect type get you? The hard part of concurrent programming is concurrency, rather than knowing what code is effectful.

For monofunctors: reliable error handling, an ability to re-interpret the same IO structure multiple times, better reasoning during refactorings due to referential transparency.

For bifunctors: the above plus explicit domain (expected) error encoding and even more reliable error handling.