Our primary use case is preventing major security vulnerabilities.
We use it as part of build our pipeline. We have a plugin that gets scanned by Sonatype as the build runs and it scans for all third-party dependencies. We haven't yet gotten to the point where we fail a build, but we make the matrix visible so we know where we need to focus. In the coming months, we plan to actually start failing builds and preventing releases which have certain vulnerabilities, from going into production.