They were able to push out a fix so fast because they repurposed the "sure, do some studies on my usage" to enable arbitrary changes to the browser that are under the control of the marketing team. And a lot of people were "opted in", thinking they had opted out.

That is 100% not reassuring. Remember Looking Glass?

https://news.ycombinator.com/item?id=15956325

Well, the marketing team has the power to tweak how ads are handled, silently, with no update action from the user.

Out of the frying pan, into the fire.