I'm not the one you're replying to, but here's how I think the Overton Window works.
Everyone has a personal Overton Window - the set of ideas that they think are reasonable and acceptable, even if they personally don't agree. When most of the personal Overton Windows approximately align on a particular topic, then we have society's Overton Window.
For example, think about gay marriage. 50 years ago, maybe even 20, 95% of society thought that gay marriage was clearly not acceptable. That meant that 95% of society agreed with 95% of society's personal Overton Windows on the topic, and so we had a clear society-wide Overton Window.
Now we have maybe 30% of people who still think that gay marriage is clearly not acceptable. We also have 40% who think that gay marriage is clearly in bounds. Of those, maybe half (so 20% of the population) think any doubts about gay marriage are clearly unacceptable. There is no position which a large majority of society finds acceptable. (All numbers made up, but I think they're in the approximate neighborhood.)
The society-wide Overton Window didn't move. It shattered.
Everyone has a personal Overton Window - the set of ideas that they think are reasonable and acceptable, even if they personally don't agree. When most of the personal Overton Windows approximately align on a particular topic, then we have society's Overton Window.
For example, think about gay marriage. 50 years ago, maybe even 20, 95% of society thought that gay marriage was clearly not acceptable. That meant that 95% of society agreed with 95% of society's personal Overton Windows on the topic, and so we had a clear society-wide Overton Window.
Now we have maybe 30% of people who still think that gay marriage is clearly not acceptable. We also have 40% who think that gay marriage is clearly in bounds. Of those, maybe half (so 20% of the population) think any doubts about gay marriage are clearly unacceptable. There is no position which a large majority of society finds acceptable. (All numbers made up, but I think they're in the approximate neighborhood.)
The society-wide Overton Window didn't move. It shattered.