"'When you have 1,700 precincts in one state, it should be a couple-month-long process of training folks, testing out the app, making sure it is downloaded, and that wasn't happening here,' Bagniewski said."
This was my first assumption, and I'll be surprised if it doesn't hold up. It's really not surprising, for all the reasons this article goes into.
So on the one hand, the Iowa Democrats should have been a lot smarter about this, and committed ahead of time to either having the app fully tested and functional a few months ahead of the caucus then everyone trained, say, a month beforehand or sticking to the old method.
On the other hand, state party leaders include a whole lot of part-timers for whom party activities are just part of their workload, and if any are particularly tech savvy its just by incident rather than any natural tendency or procedural selection method.
So normatively, yes, they should have been smarter, but empircally, no, we really shouldn't expect them to be smarter.