Raymond Chen wrote some articles about how this impacted Windows 95. It doesn't matter that program X completely ignored the documentation in Windows 3.x and so it "makes sense" technically that in Win95 that program crashes, the user experience is that Windows 95 broke Program X, and they just bought Windows 95, so they will demand a refund and moan to all their friends.
There is a limited tolerance for Chrome versions that don't work, because the lesson customers get is "Don't run Chrome" not "My middlebox is garbage". The tolerance is increased for security problems, so Google is more willing to lose say 0.1% of users because they enabled TLS 1.3 (the remaining 99.9% of users get improved security) than to lose 0.1% of users because they added a cool 3D logo and it crashes on a specific model of video card or version of Windows due to a driver bug. But losing 10% of your users is a disaster, and that was the ballpark for TLS 1.3 in earlier drafts (before it was taught to sidestep more middleboxes).
Hopefully someone will notice and bring it up with the IT or ISP, especially if the message says to do so, and that Google/internet could stop working in the future.
Actually,get more popular sites to do it, like Facebook, Twitter, Apple and Microsoft (heck, they could do it as a part of the operating system): if a lot of websites say it, users will tend to think that something is wrong on their end.
This was surely already brought up as a solution, so I wonder what the catch was, if any?
Since this would be browser-independent, the browser wouldn't get blamed, and if it's only a mild inconvenience, it shouldn't bother people that much (they have been using the web despite more invasive cookie notices). I would expect it to allow a critical number of non conformant devices to be quickly disabled as a result.
As far as I know, Javascript doesn't have low-level access to connections, not enough to run even a stub TLS 1.3 implementation.
If google deploys 1.3 and 50% of corporate users can no longer reach google's services, that would be seen as google's mistake. Moreover, that would hurt google quite a lot.
The issue is that these boxes are already deployed, and it wasn't noticed just how shitty they were until we tried to deploy 1.3 . The system has essentially rusted shut.