A setting to completely disable support for media elements per-origin would be nice. Not this "we try to determine whether a video is eligible for autoplaying" bullshit. I want an "I wasn't asking" approach of the browser literally treating <video> and <audio> as unknown tags when this setting is off.

Native support for Flash via Ruffle would also be nice.

If it's a mobile browser, I really, REALLY want a setting to just completely annihilate all the PWA stuff. No, I don't want to add this random news website to my home screen, thank you very much.

More broadly, I want most of the "progress" of the web platform undone. Sure, new CSS features, like flexbox and grid, are nice. But all those new JS APIs that (try to) turn a hypertext document viewer into a (terrible) operating system? No thanks. I want my clear boundary between the "document" and the "application" back, hence the Flash thing.

Maybe it's no longer possible due to all the click hijacking introduced by web2.