The problem is that the tech companies are paying their research/marketing departments for headlines that go "Researcher uses powerful new Saga 6.2 release to find 597 kernel vulnerabilities! (Can your company afford NOT getting their $1000/month subscription?)", not for headlines that go "Researcher spends $50.000 to find 597 bugs, then spends $25.000 figuring out 540 of them are duplicates".

Unless the kernel community starts banning & publicly shaming repeat offenders, there's zero incentive for them to put any effort in filtering out duplicates. They are mostly doing it for marketing after all, not out of a genuine interest in making the kernel better.