Disposable websites are good for job security.

There are other factors to consider, once a site turns into a desktop app replacement with dynamic content it is expected that it will change and grow, features dropped and added, styles change, the tech stack is replaced. Building a single use product to last doesn't make a lot of sense, the only part that does is the idea of maintaining "permalinks" where the content is stable and "append only", but the style may change. The world has not placed enough requirements to preserve a historical friendly web, which is why archive sites, print to pdf, and other options exist.

It is expensive to plan, and maintain sites with longevity. You don't know what the future holds and longevity might be at odds with relevance.