I don't think it's that misleading - the code is available here where the initial default registry is setup: https://github.com/metosin/malli.io/blob/master/src/malli/web.cljs#L28

I think it's apparent that the local registry being used does not contain all of the schemas available (not just :merge)

maybe the util-schema types should be prefixed? e.g. :merge -> :util/merge to make the it more explicit that they are not part of the default registry? btw this works too:

(def Merge (mu/-merge))

(m/validate [Merge [:map [:x :int]] [:map [:y :int]]] {:x 1, :y 2}) ; => true