Memorialize life online? To what end? Seems rather self important.
Why are we sometimes curious what our great grandparents did, and why don't we just put our dead in the trash heap with the rest of our waste?
For example, we consider valuable early writing on clay tablets that refers to accounting records, recipes and personal letters of ancient Mesopotamia (e.g. https://www.archaeology.org/issues/214-features/cuneiform/43...) which provide insight on how these people lived even if they provide no information on any specific major event.
That's an extremely limited, pretty old-fashioned view of history. There was literally a post just the other day about Latin grammatical genders that mentioned that linguists obsess over a few fragments of graffiti because that's all that's left that hints at how Latin was actually spoken by the commoners whose speech became the Romance languages. Other historians spend their time studying contracts and receipts from transactions involving cattle and grain of long dead Sumerian traders. There are many schools of history that are more concerned with how common people lived in ordinary and extraordinary times than great men and "important events" (e.g. https://en.wikipedia.org/wiki/History#Social_history). An important function of history is satisfying people's curiosity about the past.
One unique problem of our era is storing things digitally. If a huge event were to occur, wiping out humanity, archeologists won't be able to study ssds in thousands of years like we can study physical artifacts today.
In fact I've started the habit of deleting everything after a period of inactivity - be it computer history or social history - because it's either important and saved properly or it's not.
Certainly the world wouldn't loose heritage if random blogs, facebook, instagram, youtube went away, same as no one at large mourns the disappearance of usenet .. or myspace.
I don't know if I entirely agree. Historians of past eras work to piece together an understanding of the time based on scraps and fragments.
How rich might history be if we could see the views of tens of thousands of people, instead of hundreds?
Like you imply, the status quo for future generations looking back on this time will be no worse than what we have looking bad at the 18th century. In fact, it will be much better for future historians looking at the present. But there's a real potential to make it so much better!
The question to every answer.
¹ Only using him as an example because he is an influential person who used an online medium to communicate