The docs state that min_samples_leaf reduces the size of the tree. This is wrong. The size of the tree is not influenced by min_samples_leaf. See the discussion at #8399.

I would actually vote to deprecate the parameter, empirically 1 is always best.

I would have like to have a parameter that actually implements what I meant when I proposed min_samples_leaf but I'm not sure it's worth it. It would make for nicer trees than min_samples_split imho but I don't have the data to proof it ;)