Not really. Prior to Voldemort's first rise there was the same broad tolerance, that was what Voldemort was a reaction against.

Is there a source in canon for this? It's a really interesting take but I'm not sure where it's coming from in canon.

If it's just an interpretation of the books, I think it's a really interesting reading. But even reading it in terms of class, that doesn't mean it has to go back to what it was before: a magical, euphoric resolution of the injustices of the class system fits pretty well with Harry Potter imo.