The point is that it is possible to bring a practically unbounded amount of new dollars into the market at a cost-to-create of 0 (ie, in real terms, new dollars can be created for free) and cause inflation. Which is exactly what the central banks try to do except in a controlled manner.
Can't happen with gold, because the marginal cost of creating new gold is roughly the price of gold. The 1-2% increase in supply from mining isn't going to cause real inflation in gold that behaves anything like inflation in the dollar. Supply increases to meet demand, but the value that the gold represents does not change.
If someone finds a super-nugget the size of a cargo ship to mine that might change, but that isn't what the original point by joe_the_user was going to.