Aside from all points you raise I find the discussion about battery life a little absurd in light of how negligible it is compared to the impact poorly written JavaScript in the context of web apps. For example, I noticed this morning that my bank somehow pins one CPU thread to 100% usage whenever I have their internet banking site open, even when nothing is being done. AFAIK there is no cryptocurrency nonsense going on, and the UI latency is pretty good too, so my best guess is that their "log out automatically after ten minutes of inactivity" security feature is implemented through constant polling.