Arguably they could degrade more gracefully by just starting slightly sooner when they have some resources to manage but they successfully ignored the problem until it became someone else's problem. At this point I don't know that any solution would be much better than simply running a daemon like earlyoom in practice. I'm just surprised that desktop distros ship with Firefox which absolutely can in edge cases leak gigabytes of memory but no good way to deal with misbehaving applications after memory is exhausted.