Answer:
They did not. To religious Jews today, they are nothing more than a curiosity, especially in view of the likelihood that the provenance of many or all of the scrolls is linked to the Essenes, a tiny, non-traditional breakaway group.
We rely upon the Masorah (Masoretic text), which reflects our national tradition.
However, the DSS confirm that the texts of the Tanach (Jewish Bible) used today have not been altered in over 2000 years.