It is even worse. You can recover from backups but that implies that you already know at which point you destroyed your data and how fast you discovered that – if that ever happens. Imagine you're collecting data over a substantial period of time (maybe do calculations based on it that influence how you're collecting further data) and you're very smart and backup all your data let's say every day. The problem is if your data gets defects due to the file-system it is very unlikely to detect that. You can run your system for like a year without apparent problems whatsoever. Lets say that error accumulates and you eventually detect this by accident. Your backups are pretty much worthless ...