This is an interesting statement. It sounds awful definitive (I can't for the life of me figure out what word I'm looking for here), though. I mean if it were truly "lost" then would people even still refer to the individual marca's flavors anymore? I guess I'll be putting my words to the test with Kirk's little bet, but I have trouble believing someone thinks that Bolivar or Partagas, just for examples, flavors have disappeared. Or am I misreading the statement? To say that they've lost SOME of their distinction I'm sure could be argued (I wouldn't know as my frame of reference is late 90's and beyond), but to simply say that the distinct flavors are gone seems an overstatement to me.
Perhaps it depends on the marca. I agree that, to me, some marcas have a distinct flavor (when rolled correctly and with at least a little rest on them), such as Bolivar, Partagas, Cohiba, Trinidad, HdM, maybe others. But then there are some marcas which taste rather "generic Cuban" to me, though my experience with them is limited.
I did just have a Bolivar RC, though, that was definately off. It tasted very generic until the last third, and even then it was only a hint of that Boli profile.