Nobody attacked Firefox successfully, but that's hardly a point against it. I don't know what "made no improvements at all in previous 2 years is supposed to mean", either, since we had just released a major overhaul of the optimizing compiler a few months before Pwn2Own: https://hacks.mozilla.org/2020/11/warp-improved-js-performan....
> One change in the 2016 event is that the Mozilla Firefox Web browser is no longer part of the contest.
> “We wanted to focus on the browsers that have made serious security improvements in the last year,” Gorenc said.
https://www.eweek.com/security/pwn2own-hacking-contest-retur...