Well, usually no one gives away stuff for free. So, there is an initial and continuing cost.
*IF* you go to WDW yearly, and *IF* you stay at a deluxe resort every time, then Disney's "timeshare" is cheaper than doing that.
But it does commit you to going, or to try to sell off your points if you don't. And you might tire of a yearly WDW trip, or your financial status changes that you can't afford the yearly fee.
It's Disney's way of committing you to go every year.
If plopping down tens of thousands of dollars a year for entertainment makes one blink... it's not for you.