Witnesses want to have ten thousand minnow votes instead of one whale vote. The reason is that a whale could at any time remove a vote which will cause a witness rank to plummet right off the top 20 rank. Even if the witness is not on the top 20 rank, their earnings can be significantly reduced causing their earnings vs cost to run a node to be very negative.
With many minnow votes, some minnows can remove their votes and it would not impact the witness ranking.
So the more minnows that we have signed on, the more attractive it is to witnesses. We do have power in numbers.