Certainly, you can’t block the vents; it’ll prevent operation.
Drying does kill the batteries, and when I used a 312 HA years ago I would use it infrequently and the batteries would always be dead by the time I picked it up again (even having opened the battery door to turn it off while stored).
What I’m hearing from people (and I LOVE empirical evidence) is that the operational life of the batteries ends before the dry-out time even when cycled daily in dryers of various kinds, so it’s not much of an issue.
But I’m confused by that article that Sierra posted. Assuming it’s accurate, I wonder what the issue could be? Is it too much moisture diluting the chemistry? Or is it Neilk’s vent-blocking theory coming into play? It wouldn’t take much moisture condensing at those tiny vents to block off the air. And the cells do need air.