It occurs to me that one reason for the topos of the successive condensations of an immense book, at least for narrative literature, is that the audience of Indic literature derived an aesthetic pleasure from the size of the narratives, an experience of a sort of oceanic feeling.  Thus the presence of an immensely large work behind a merely large or medium-size one gave prestige to the latter, plus perhaps a pleasurable feeling of being plunged into a part of the largest narrative ocean, even though that ocean was not accessible because it had been lost or one couldn't afford a copy of it.  It is a radically different aesthetic than that of Greek and Latin literature.

Allen