I agree that deleting data is probably difficult from a data integrity standpoint. However, unless being able to delete data is made a priority the situation is

I agree that deleting data is probably difficult from a data integrity standpoint. However, unless being able to delete data is made a priority the situation is not going to improve. It's a more general problem and certainly not specific to Facebook but unless there is some motivator I don't think a whole lot of engineering effort is going to be put in to it by anyone. From a technology standpoint it seems it's more desirable to just keep throwing storage at the problem and spend time working on ways to store and manage even more data. Data is valuable after all, so the incentive is there to accumulate and process as much of it as possible. That's exactly why we need some form of external stimulus (eg: laws) to force people to work on the problem of how can we be getting rid of data when we need to without breaking everything.