Yes - I think we can conclude that these techniques are both too complicated and not ergonomic enough as of now. If that does not work in Scala, it will work even less in Kotlin (where many people go when they find Scala too complex).
I think something like algebraic effects can definitely be ergonomic and understandable, but a language definitely has to be designed for it. Algebraic effects are like exceptions in a lot of ways, so I think people will be able to understand them. See Effekt [1] and Koka [2] for languages that are designed with them in mind.
