Read the paragraph about halfway down:
The erdstall surely could not have been built with storage in mind, since their length and narrowness offer no advantages over a conventional and convenient cellar. And while three brave explorers in the 21st century once spent 48 hours in an erdstall, crawling to new sections whenever oxygen became scarce, it seems unlikely that they would have been constructed as hiding places, even temporary ones. Though they could have provided refuge for a small family, why would they be accessed from such public spaces? Or be too small for a large man or pregnant woman to fit through? The lack of exits is a further strike against this theory—if enemies became aware of such a tunnel being used as shelter, it would quickly become a death trap for its inhabitants. Besides, in either of these cases, one would expect at least some goods to have been left behind—remnants of food or clothing, cached or dropped valuables. Instead, there is nothing
You also need to look at the locations and context. There are several of these things in the region my family comes from and at the estimated time they were built there were no invaders or other problems that would justify using them as shelters. Not to mention that if there were, you'd hide your family in existing shelters in the surrounding forests or hills, not some cramped underground deathtrap.