The little players not having data is a win in my eyes, because those are more likely to get breached or sell data to the highest bidder.
> This only works in Google Chrome
Regardless of Firefox abiding by the standards (or doing what Chrome does) or not, this was always going to be the case, and so it isn't that big a deal.
> Trackers that offer a widget you can install on your server will win.
This is already a thing thanks to the popularity of content blockers like Pi-Hole and uBlockOrigin. Firefox's move here is another nail in the coffin for third-party tracking through third-party servers. At least, first-party tracking with third-party "widgets" means first-party would need to shell out the cost of running that infrastructure.
> The web will break.
The web always has been :)
> Those of us who will stick with Firefox regardless are in for a world of pain, and not a lot of gain.
For me, Firefox seems to be making decisions with user's security and privacy in mind, and I see that as a net positive. As a long time user, it is the only reason I use Firefox.