Sure, but that doesn't change the fact that the dividend affects that stock price.
I recall an example used a while back, not sure if I came up with it or not, might have been samclem? But consider this:
You have a car to sell. You have 10 serious buyers in your driveway take a serious look, and ask each of them to write down their offer on a piece of paper and you'll take the highest one. You have also pointed out the envelope on the dashboard with $1,000 cash in it.
You collect the bids, and then say - sorry, I need to remove the $1,000 cash from the deal. I guarantee you everyone will say, no fair, unless they are all allowed to drop their offer by $1,000.
How can it be otherwise?
And yet, each person may have put a different value on the car and cash. And each may have picked a different number on any given day. But I'm certain everyone would consistently say that removing $1,000 cash from the deal made the deal worth $1,000 less.
That happens when a stock goes ex-div, there's just a lot of noise riding along.
-ERD50