At some point, the random physics crap that goes on at the atomic or subatomic level would tend to alter your data. Vibration, atomic movement, you name it. Already, we have systems that cosmic rays can screw up. At the very least, such systems would probably have to operate at very low temperatures.

When you deal with this, you start having to duplicate your data or systems to make sure everything is stable, and then you get larger again.

It goes without saying we are nowhere near this "tell you three times" threshold point yet, so we have a lot of room for growth. Or shrinkage. Or something.