This rule has really only been in effect since 1993 or 1994 after some of the commem programs got little out of control. Before 1994, there were quite a few coins with mintages over 500,000, including the Bill of Rights, Mount Rushmore, and then you get to the big boys, like the 1990 Ike with 1.1 million proofs, the 88 Olympic with 1.4 million proofs, the 87 Constitution with 2.7 million proofs, and the grandaddy of them all, the 86 Statue of Liberty with 6.4 million proofs! The $5 SOL sold out with a combined production of 500,000 and for a year or two after the sellout, that coin was selling for $500! Now you have things like the 2002 SLC Olympic $5 with a mintage of 5,727 and it's not worth much more than melt! Granted, it is an ugly coin, but come on!