30,000 studies are a lot, but are only 0.2% of studies using cell lines, per my light reading of the paper. Moreover, some results will still generalize, as even if contaminated, they may still be cancerous cells of another lineage.

In some ways I think these kinds of things are more about having the time and resources to keep things organized. It is a constant struggle in labs by people who may be expert biologists, but amateur database managers.