On one hand I agree, but on the other, if you use 01-01-1970 everywhere, you'd be that one guy (with the IIIII plate), because as I still believe, the amount of people using that date everywhere would never be big enough to void the fields value to the ad networks.

Which is why I think using a random one is best, it at the very least changes my data for each account I own.

But in a purely theoretical way, I do agree. Practically however, I don't think it will work, since not enough people will do it.