> Maybe/Either get talked about because they're the simplest Monads you can make, but it makes Monads sound like a spicy container type.

Actually "spicy container type" is maybe a better definition of Monad than you may think. There's a weird sort of learning curve for Monads where the initial reaction is "it's just a spicy container type", you learn a bit and get to "it is not just a spicy container type", then eventually you learn a lot more and get to "sure fine, it's just a spicy container type, but I was wrong about what 'container' even means" and then settle back down to "it's a spicy container type, lol".

"It's a spicy container type" and "it's anything that is flatmappable" are two very related simplifications, if "container" is a good word for "a thing that is flatmappable". It's a terrible tautological definition, but it's actually not as bad of a definition as it sounds. (Naming things is hard, especially when you get way out into mathematical abstractions land.)

There are flatmappable things that don't have anything to do with ordering or sequencing. Maybe is a decent example: you only have a current state, you have no idea what the past states were or what order they were in.

Flatmappable things are generally (but not always) non-commutative: if you flatmap A into B you get a different thing than if you flatmap B into A. That can represent sequencing. With a Promise `A.then(() => B)` is different sequence than `B.then(() => A)`. But that's as much "domain specific" to the Promise Monad and what its flatmap operation is (which we commonly call `then` to make it a bit more obvious what its flatmap operation does, it sequences; A then B) than anything fundamental to a Monad. The fundamental part is that it has a flatmap operator (or bind or then or SelectMany or many other language or domain-specific names), not anything to do with what that flatmap operator does (how it is implemented).