An engine component separable from the UI (which was XUL and thus Firefox initial advantage that gave it popularity), deeply extensible via plugins, tunable (it would be so frigging cool to be able to turn off sections of).
What it was needed for when it was popular.
Not a Chrome alternative with a different engine.
Somehow every time I mention XUL and XULRunner people mention that one can use PaleMoon or that XUL is incompatible with some security and stability changes and so on.
I know that. I don’t mean literally XUL, I mean low-level access to the engine. Allowing it to be used for things like old Conkeror and such, or just customizing Firefox as deeply as it was possible in olden days.
Yes.
I’d also want a standard, so that it wouldn’t be monopolized into one bigger platform, like with GMail.
And probably servers should have some kind of zero-knowledge protection, so that such a client-side filter would be the only one applied to the information. Maybe with ability to subscribe to filters published by someone else, of course, or kill lists, but always preserving transparency and choice.
EDIT:
I think NOSTR is kinda similar, only it has public keys as identities, just so. In general its cryptographic mechanisms are used as intended, but in a very ancient way. It’s too simplistic.
New Freenet (Locutus), I think, is going to be a platform where one can make such an application and a thousand others.