A covered calls is a synthetic short put. If I'm the long call and I exercise a long March 87.50 call, I end up long stock and keep the dividend. But now to replicate what I had before, I need to buy a 87.50 put, which cost more than the dividend. Then the buyer has a synthetic long call. In addition, I have to consider the cost to carry the stock positions. If I had that long call, I would find more value in holding it.