Sorry but the hyperbole doesn't help your case. The OUAT show runners seem to be looking at classic iconic characters whom they have the rights to use either by licensing or the public domain. A Disney connection is also a plus. Places like Wonderland, Oz, and Neverland are recent creations in the grand scheme of things.( The latter two from the early 20th Century) If a certain magical Nanny shows up, her literary debut was in the 1930s. So a character from a book published in the 50s isn't all that of a stretch.Robin Hood is usually set in a certain time and place (often England in the 16th/17th Century) and plays more as historical fiction. Not much magic in most tellings.
Frankenstein was published in 1818 and takes place in the 1700s. Long after the time most fairy tale are set. Grimm's Fairy Tales was first published in 1812 and the tales were old even then. "Cinderella" has been traced as far back as the 6th Century, BC.
And to this timely history lesson I say... see my last post.
Non magical characters aren't off the table either as seen with Robin Hood and Dr. Frankenstein. Frankly I'd like to see a OUAT land that features American legends like John Henry, Casey Jones,Pecos Bill and Johnny Appleseed or one drawn from Native American myth.
Obviously, the second paragraph of that post distracted from the most important part, so I will rephrase it here:
You win. Robin fits. Cruella fits. Frankie fits. Every half-assed half-magical whatsiwhojits the producers want to put in fit. I don't care. I refuse to continue arguing over the fitness of fictional characters for a show I officially stopped watching on Sunday. So I concede. You win. Enjoy the next half of the season.