In Nominative^x, Predicates^x, Conversations^x

I would say "She was I", but Kooyeen delights in pointing out that I'm in a 1% minority. It comes down to, what do you mean by "correct"? - and what do you mean by "allowed"? - and what "register" would you like to represent? I like to think of the song lyric from the musical, The Man From...

The so-called object pronouns are actually acceptable in the "predicate nominative" position according to many modern grammarians. Some say that it has been only the tendency of English grammarians throughout the centuries to create rules for English in imitation Latin grammar that has led to...