The point of your opponent's argument is that measured age should be an indicator of maturity and stability of frameworks and toolchains.

In JavaScript, it is not. So you claiming 10 years as a time frame in your response is in bad faith, because you certainly know that code written 10 years ago is 100% incompatible with the modern versions of the same frameworks.

Next.js keeps breaking code so there's that.

React has broken compatibility about once every two to three years. Next.js feels more like every other day.

These are not stable targets, which means your code is out of date next year.