Fractured Axel is still relatively active.
In some ways the periodic vanishing of sites helps with vitality. Stale links that point to other long-dead sites go away and new descriptions are written. People ask old questions that had been removed and get new descriptions that are more current. Topics that were settled one way get an opportunity to be revisited.
There are painful parts, there is information that gets lost forever. Some historically interesting bits will be lost. There are old technical details, such as knowing that such-and-such kite required some specific type of spar, or descriptions about rare and unique kites that will be lost which other people may someday want to know.
As sites grow for years or decades, pruning out the deadwood gets harder. Even if you look through the oldest posts here on KiteLife -- back from when it was reset and migrated to the current system about 15 years ago -- there are a huge number of posts with links that no longer work. Those include images and videos that don't show, links to documents that don't exist, plans for events long past, and references to stores that are nothing but memories.
It's nothing new to the web. I was going through some old books recently, including some paperback books and other materials from the 1940s, and several had ads in them that were long out of date. Many tried to cross-sell other books from the publisher, which I'm sure are long out of print. A few were possibly still relevant, like getting Time Magazine for a year for 25 cents, but just like links on the web, most refer to long-forgotten products and old business ventures.
I considered hosting an archive, but decided against it. The site is/was mostly banter and casual chat. While there are some unique and irreplacable gems, they are so sparse that it isn't worth the storage and hosting cost.