You can see why everyone had such a problem with it coming from classical physics and nice simple causality, including all the pioneers of the field.
Everyone knows Einstein’s quote “God does not play dice with the universe”, but my favorite is somewhat less poetic:
“I don't like it, and I'm sorry I ever had anything to do with it.” - Erwin Schrodinger
(Quite a good quote for a T-shirt that. Maybe sell well in post Brexit Britain.)