Of course there can, you will often see a company involved in a secondary or some other form of dilution have its PPS go on a run.  Shares are added to the available supply, thus creating liquidity...and the PPS will often soar, it happens all the time.

That's why the subject line is that liquidity is a two way street.....obviously you need buyers, but there also have to be others willing to sell for the market to be effecient.  I think of MMs almost as bookies establishing a point spread on a football game.  The bookie doesn't care which team wins, all he cares about his that there's roughly equal betting on both teams....then he makes his juice.  In market terms I would replace the word juice with brokerage fees.