Does it embrittle rubber or plastic balloons? Hydrogen is so cheap and easy to make, you could have a single bottle that feeds into a blimp, refilling it when enough has seeped out.
But yes hydrogen is cheap enough that refillable bottles and more leakage is cheaper than helium in terms of just the features of lifting gas. Hydrogen reactivity makes for other materials, engineering, and maintenance challenges that can be ignored with helium.