Sure but a corresponding up-side for those who use the benefit the rooms offer. That's a wash - one guest for another.
Anecdotes relayed online doesn't constitute significance of any metric.
I didn't say it wasn't happening. I said I doubt it happens "a lot", meaning as a significant (to Disney) percentage of all rooms booked.
There is no reason to believe that. While Disney runs a pretty high load-level, the number of days per year that they're totally sold out is limited, and even when they are, there is no indication that guests will simply not visit WDW if they cannot get a room on-site at late notice. Generally, the folks who are rabidly devoted to staying only on-site are the ones that book early, before the rooms sell-out. Regardless of all that, Disney has far better metrics on what affects their bottom line, and far of a vested interest in accurately and evenly viewing those metrics. I'll trust their actions are based on better knowledge and experience than your opinion or mine would project.
Even if that were true, it would mean overall better service for the guests who stay, since there would be more staff than the smaller amount that cost-consciousness would dictate.
It is enough to say that you personally don't like the prospect. That I could understand and respect. Perhaps you feel that your family's enjoyment of your vacation, specifically, is undercut by the prospect. I can see how that could be the case. However, bringing this back to the point of this thread: Other families differ from yours, and there are other stakeholders in the system, including investors, who have as much right to have their objectives respected.