Use After Free Use After Free Use After Free Use After Free Use After Free Use After Free Use After Free.
I would be more satisfied if they gave a proper explanation of what these could have lead to rather than being "well maybe 0.001% chance to exploit this". They did vaguely go over how "two" exploits managed to drop a file, but how impactful is that? Dropping a file in abcd with custom contents in some folder relative to the user profile is not that impactful other than corrupting data or poisoning cache, injecting some javascript. Now reading session data from other sites, that I would find interesting.
You should generally assume that in a web browser any memory corruption bug can, when combined with enough other bugs and a lot of clever engineering, be turned into arbitrary code execution on your computer.
The most important bit being the difficulty, AI finding 21 easily exploitable bugs is a lot more interesting than 21 that you need all the planets to align to work.
If you can poison cache, you can probably use that a stepping stone to read session data from other sites.