I think you're partly right, but I think another aspect of it is how new all this technology is. We completely dropped the "old" way of doing things (carefully take photo, get it developed, store it in an album) and replaced it with the current way (take lots of photos, upload them all to some service, share with friends) in a decade or less. Most people simply haven't accumulated all that much history on these services yet. It'll be interesting to see what our personal histories look like once this technology has been around for a few more decades. Things like the Facebook timeline may become increasingly important, or we may all abandon curated histories because (as you say) information is so easily retrieved now.