After this price drop I agree with you. It's still free market but all campaigns need to raise their rates if we think about $ value.
It's still up for the campaign managers to up their rates. After all, even if $ value of bitcoin goes down, would the quality of posts made by users go up if campaign managers raise their rates? They would still get the same level of advertising without any actual effect on their service, so why raise it when they really get what they want?