The fact that we need a "stop the madness" app for Safari is proof of Safari's insanity.
If Stopthemadness actually works reliably, it is also an existence proof that blocking video autoplay is possible, and that Apple is simply not fixing the "never auto-play" setting in Safari.
Perhaps Apple and Mozilla should just remove the "never auto-play" settings in Safari and Firefox and say that they are doing so in order to empower web sites and adtech companies (including Google/youtube, who pays them a lot of money) to force you to view unwanted video advertisements.