What makes monads in Haskell interesting is that someone identified them as a pattern, generalized their usage, and then syntax was added to the language that lets you compose them in a natural manner. Sequential execution itself "is a monad", but in most languages we express that using something as simple as ";" or "\n": Haskell effectively generalized the idea of statements to support anything that is monadic, which is why identifying something as a monad ends up becoming so interesting in Haskell as opposed to many other languages.
And Haskell gave up rich control flow (break, continue, early return) by doing so. If you trace through what having those statements means for monads as a first-class concept, you find that the situation becomes very much not that simple.
