If we did not digitally document our life, our ‘self’ might cease to existThat is quite a claim; but, in all likelihood it is as specious as it is compelling.
The logical flaw lies in that verb "document." Digital devices do not document. They capture signals that would otherwise stimulate our visual (and sometimes auditory) sensory organs. In the latter case those signals are, for all intents and purposes, meaningless until mind imposes order on them through a process that I like to call "sensemaking," having picked up that word from former colleagues.
Documentation is a similar process by which we try to make sense out of bodies of objective data that confront us (which may include the images we have captured on our portable devices). In other words documentation is, in a sense, an attempt, usually through writing, to reproduce the results of sensemaking achieved by mind. This brings us to Malkani's scare quotes. Many researchers of the nature of consciousness, such as Gerald Edelman and his acknowledged predecessor Friedrich Hayek, have made compelling arguments that "self" is not only the "engine" of sensemaking but also its product. In other words, to use Malkani's turn of phrase, "self" exists as a result of how we make sense of the signals we capture. It is neither the process of capturing nor the signals themselves.
This allows us to turn Malkani's conclusion on its head. The more obsessed we get with capturing the signals around us, the less obliged we seem to feel to "make sense" of them, which is to say to "document" them. The reductio ad absurdum is that we shall become mindless drones, sucking up all of the signals around us but leaving interpretation to someone else (except that there is no "someone else"). Rather than compensating for dementia, an obsession with capture contributes to further erosion of the capacity for sensemaking. Welcome to the world of the "hollow men!"