My professor once said: the only thing that we'll still have in 80 years is the file system. Always bet on the file system.
This started out in my quest to be sure that i can not trapped by an app, and so i can safely export my data...but, nowadays, it has extended a little into the tinfoil hat thinking - fairly or not - where i ask myself: "why does this app not disclose where its files are stored, *what do they have to hide!?!*" ...which feels like the universe is nudging me more and more towards either text-centric methods, or the simplest, open source style apps, etc. :-)