Algebraic effects (at least in multi core ocaml) are a restriction on monads because the function passed to bind in a monad may be run multiple times whereas the equivalent continuation after some effect may only be run once. Therefore one cannot use algebraic effects to eg do the equivalent of what the list monad does.
Hmm... Maybe I need to look at multi-core OCaml more closely, but I don't think it's true in general of algebraic effects (or at least its freer monad variants), as in I'm pretty sure I can emulate a list using them. In particular I'm pretty sure I can do that with `Cont` alone.
You're right, the linearity restriction on the handler continuation is a peculiarity of multi-core OCaml and really more of an implementation detail.
However, it is also true that you cannot encode, e.g., the continuation monad using (typed) algebraic effects. The precise relationship isn't that simple, but this paper:
