> The sandbox is the world at this point, closed software is retreating every day to smaller and smaller niches. You use browsers developed in the open, on websites built with opensource software. Even on mobile, the foundational frameworks are open - the most popular mobile OS is opensource. Obviously it's not a perfect state of things, but it's a world apart from the bad old '90s, and we did get here by keeping the Overton window firmly rooted at one end, thanks in large part to the FSF.
The only open source browser with significant usage is Firefox and it is in the single digits. Chromium might be open source but it is not what people use, it's in the other category in statistics. People use Chrome and Edge and Safari and Opera and Vivaldi and none of them are open source. The number of people using AOSP is also vanishingly small. Most Android users use one of the proprietary variants of Android. The year of the Linux desktop never came. The most popular Linux variant after the proprietary Android is the proprietary ChromeOS. And, worst of all, many services that before didn't even involve a computer (ordering food, calling a ride, banking, etc.), now are done through closed source software. It is getting harder and harder to live without proprietary software.
So absolutely not, the sandbox is not the world, the sandbox is getting smaller and smaller in comparison to the world.
The argument was not to no longer hold the Overton window pinned. The argument was to advocate for consumer rights and protections in LAW. Free software advocates are vary much interested in right to repair because right to repair also counters tivo-isation. And the world is much more tivo-ized than it ever was. That the world became so tivo-ized is also a sign of how ineffective the FSF has been at countering a threat they were among the first to draw attention to. You can have all the free software in the world and it is of no use if you can not run it on any hardware.