My point is that it's a diversity of opinions (maybe; they tend to be closer together on the important things, too, demographics predict politics fairly well after all) and of hobbies or interests, but not of backgrounds, i.e. where the rubber meets the road. I understand that people usually do not mean "the conservative child of lawyer A and the progressive child of investment banker B chat about their shared interests with the apolitical child of entrepreneur C", but "the child of a lawyer, the child of an office worker chat with the child of a day laborer".
Again, I don't mind it not being or having been like that, I don't see any intrinsic value in diversity by itself. Calling it diverse just sounds like a misrepresentation of what it was.
(The only exception is if by "diversity" you mean "exact proportionality of representation"... but that's not the same thing. If you want to say that, go ahead. At that point I will agree with you that there wasn't exact proportionality of representation... but then, there isn't today either, nor is it even clear how one would get there, especially as you crank the requisite "exactness" up. Two decimal places? Four?)