The thing that sets E2EE apart from HTTPS is that HTTPS requires nothing from the end user. It just works. And as a site owner, you just set it up once and forget about it.
True, but one is also free to study the UX solutions implemented on platforms such as iMessage, WhatsApp, and Signal, which all have strong E2EE and see plenty of mainstream usage.
> [...] HTTPS requires nothing from the end user.
Depends on how you define "nothing". We've collectively put an insane amount of work to bring HTTPS to where it is today. Also, HTTPS continues to rely heavily on each server operator's skills and diligence.
There's also plenty of edge cases where HTTPS clients need to go an extra mile, such as containers (many base images do not include a cacert bundle), IoT/retrocomputing/other underpowered devices, and so on. There's always a cost, but it's usually worth it.
Effectively making it useless for so many people, the reason is due to e2e encryption.
In contrast, Telegram has groups with 1000s of participants, but only possible as they don’t use e2e encryption.
On iMessage, your keys are managed by Apple. You effectively fully trust them (which seems to be the assumption in most of Apple products anyway). I wouldn't call this a "real" E2EE implementation.
In WhatsApp, you're limited to one device logged into your account, and the rest are proxied through it. And message backups, those are annoying.
In Signal, you have all those stupid backups too, and while you're able to log into multiple devices (it seems), your past messages don't load "for your own security", and there's also this stupid time component so you get logged out on your computer if you haven't used the Signal desktop app for some weeks (which I don't).
Whereas on Discord, Telegram, Slack and other IM services without end-to-end encryption, you log in on a new device and that's it. You instantly get access to all your messages since the beginning of time, and stay logged in forever.
On iMessage, you can verify keys now.
I'd argue there are many scenarios in which this might be preferable to a lengthier/wider supply chain. Personally I'd sooner trust Apple than Microsoft+(Lenovo/HP/Dell/...)+(Intel/AMD/Qualcomm/Broadcom/...)+(every device with DMA (PCIe/TB), unless you trust your IOMMU)+(.../...)... (you get the point). And the alternatives to Microsoft are each its own kitchen sink.
> In Signal [...] your past messages don't load "for your own security" [...]
I agree that this is quite annoying. HTTPS clients resolved a somewhat similar problem (usage of self-signed certificates) by trusting the user to make an informed choice. I wish Signal would trust their user base to make their own choices there as well.
> Whereas on Discord, Telegram, Slack and other IM services without end-to-end encryption, you log in on a new device and that's it. You instantly get access to all your messages since the beginning of time, and stay logged in forever.
Same with iMessage. Whether this is a feature or a bug, depends on your threat model.
But we're in a situation where we don't even get to make an informed choice - every solution (as you pointed out) comes with its own bag of UX shortcomings. These trade-offs should be user choices, not something the vendor forces upon you. But these are not fundamental shortcomings of E2EE as a concept, but particular issues with its different implementations. WhatsApp shows you can restore messages from a backup; Signal shows you can have "real" multi-device presence; etc. If we could spend 1/100th of the effort we did to push HTTPS everywhere, E2EE could be just as ubiquitous today.
Not really? You can choose whether to upload your recovery key to iCloud or not. The software abstracts over the details of course, but Signal does that too. Unless you're arguing that it's impossible for closed source software to have "true E2EE", which may have some merit, but Discord is proprietary, and something is better than nothing.