Is there any evidence that this really matters on top of the protections and limits that are already built in and obscured from the user? There's such a cult around this feature, but I'm not convinced.
What I don't understand is do any of the OEMs giving this feature also combine it with passthrough power? So besides not charging the phone at 80%, it would keep it working using the wire instead of the battery.
Fair question. I'd assume that the buffer which the BMS/low level firmware reserves is relatively marginal. Having too high a margin at that (low) level would take away a lot of capacity and might make people mad