Sure. But that isn't end-to-end encryption; that's a weird key escrow thing. It would be a little strange for Matrix to officially support that kind of use case

Sure. But that isn't end-to-end encryption; that's a weird key escrow thing. It would be a little strange for Matrix to officially support that kind of use case, since it's indistinguishable in the general case from dangerous, privacy-compromising forms of key escrow[1]. [1]: https://en.wikipedia.org/wiki/Clipper_chip https://en.wikipedia.org/wiki/Clipper_chip