IMO blocks are not something to be careful about in ruby. If you don’t use blocks you are the weirdo in this language.

Method missing is a different beast altogether. I would probably avoid it nowadays.

There are legitimate uses of method_missing (though often you'd want to call define_method dynamically instead for performance), but they tend to be when you use an object as a proxy for something (say a remote API) where you genuinely can't know the set of messages the object might need to be able to receive.