To give some context on why JMAP is relevant today, you might want to read this answer in the conversations FAQ [1]. It basically states that XMPP powered Apps are having trouble fighting against the battery saving software because XMPP is stateful. JMAP, on the other hand, is stateless.
As protocols are meant to connect different implementations and bringing more protocols for the same task quickly hurts the interoperability (before bringing some improvements in the long-term), I am skeptical to the effects those new protocols bring to the ecosystem. I am aware that JMAP was born more out of the RESTful requirements of an HTTP based App, but in general, I am wondering where this road will lead us.
Note that "RESTful" in JMAP's case means "everything over JSON HTTP POST", methods to be invoked are embedded in the JSON request.
As for XMPP battery consumption I didn't see major problems, Conversations.im is always <1% (I just checked and it shows 0%). On the other hand Conversations can use push to optimize battery usage.
Yes, in fact, there is absolutely no reason to restrict well-built apps like conversations from consuming battery automatically. Even without Google Push Notifications the battery consumption is quite good.
So it is pretty obvious that the vendor built battery optimization software does more bad than good.
As protocols are meant to connect different implementations and bringing more protocols for the same task quickly hurts the interoperability (before bringing some improvements in the long-term), I am skeptical to the effects those new protocols bring to the ecosystem. I am aware that JMAP was born more out of the RESTful requirements of an HTTP based App, but in general, I am wondering where this road will lead us.
[1]: https://github.com/siacs/Conversations#but-why-do-i-need-a-p...