I don't think anyone checks their artifact signatures. I've changed signatures several times over the past few years (every time I get a new laptop I forget to copy over my keys) and haven't heard a peep from anyone using my open source libraries who actually noticed the change
We notice and costs several hours per month to handle. A malicious party can slip through, single contributor software is classified as a high risk but XZ utils were not classified as such so we would have missed the Jia Tan incident.
