I do like the way Rust has language editions which let you work around this, at least partially.
Mostly though I don't care if we break old stuff. It happened all the time when developing for the desktop. People just dealt with it. The ones most impacted are lazy enterprises and I have no sympathy for them.
The loss of being unable to access old information is unknowable and therefore infinite. People can't just "deal with it." Every year there is more technical baggage that someone new to the environment is just supposed to learn. At some point it becomes an impregnable barrier.
If you start telling people they have to install an obsolete web browser, and then an obsolete operating system, and then patch the drivers because all the hardware doesn't support it anymore, you have effectively gatekept information that was once available in the open web to the tech elite.
Yes, "tech" is redone from scratch every 6 months so 5 years ago is an eternity, but there are plenty of fields where 30 year old information is just as invaluable as something published today.
Nobody is maintaining webpages published in the 90's. Nobody is going to update them. They are just there, sitting on some university's server that barely gets any hits. The author probably died 12 years ago and nobody even remembers who is responsible for it or that it's running. And it's in everyone's best interest to keep it that way: online.
I think the cost is too high. If people want that information then they will find a way. If not then it probably wasn't that valuable.
The reality is that we have already given up in many areas, try and run a 16 bit Windows application on Windows 11, try and run a Node app you haven't updated for ten years, try and run early versions of OS/X and see how much internet dependent functionality has been lost, try and view an email with linked assets, try and run a web page with a Java or Flash applet.
The only people who can find a way are technical people. The average person can't do it.
And we can't tell how valuable it is because we don't know what we are losing.
If we burn down the Library of Alexandria, was there anything valuable in there? We don't know, because it's all burned. It's inaccessible. It's too much stuff to verify before doing it, and we can't tell after we do it, so I'd rather we don't burn down the whole thing since we don't know what's inside.
And every time it does happen, it's a massive loss.
You have no idea how much I grief the fact flash games are no longer a thing. If newgrounds still had flash today, the Internet would be a much better place.
Mostly though I don't care if we break old stuff. It happened all the time when developing for the desktop. People just dealt with it. The ones most impacted are lazy enterprises and I have no sympathy for them.
Clinging on to the past stifles innovation.