I think it is important to make the distinction that the act of externalization or sharing of an experience as some have mentioned should not be completely written off. There is a positive way to externalize our experiences, and it requires more effort and thought. As a general rule of thumb I would argue that experiencing something, reflecting on the experience afterword, and presenting it in a meaningful way meant for longevity is the method most preferred. Sometimes we can't wait until after the moment. Sometimes we need to take a picture now, but the filter and the posting can happen later. The insta-thought that you had that you'll forget may need to be jotted down, on the phone, or in a notepad, but it should not require a complete entrance into social media and draw you away from the moment like it currently does.
The best experiences I had in Facebook was not waiting for every single picture to come out and following someone's life as it happened, it was waiting for when that big album from someone's trip was finally uploaded. There, in one stint you could immerse yourself vicariously in the experience that someone had. When a breakup would happen, instead of reading the vacillating short thoughts and daily experiences of someone going from gleeful to miserable, it was always better IMO to read a reflection that someone had after several months of thought and introspection.
There is a proper way to use social media and share, and as we are, aren't using it to it's full potential. Remember when your papers in school had a minimum word limit? The point was that you had to put in effort when you wrote something. Instead, we get a max of 140 characters and the incentive to share NOW without any real foresight into what we post. That should change, I hope it changes.