Yeah, it makes me uncomfortable knowing that SO much information is going to be lost with mass comment deletion or whatever else. Luckily as abff08f4813c said there are archives and also this (info) which might be the same thing.
There are also extensions like this in case you want your own local copy of single pages so you're definitely not going to lose them.
(Also thanks from a K400 owner, haha.)
Not sure if it's the kind of thing you had in mind, but I like TiddlyWiki for certain things like note-taking. (See here for saving/hosting options).