Regarding the SP4 requiring energy to shut down, I can verify that this isn't an issue relating to this matter of the battery drainage. Yesterday, after using up the charge of the SP4 all the way down to 5%, I charged it all the way back up to 100%. From there, I performed a full shutdown, then left the SP4 on the charger for an additional minute afterward, then removed the charger from the SP4. This morning, 20 hours later, I powered on the SP4. The charge was reported at 87%. So a 13% charge drop in a 20 hour time span after the SP4 was fully charged, fully shut down and then removed from the charger one minute after the full shutdown.
Again to reiterate from a prior post regarding this issue, there is an online Microsoft community support forum thread elsewhere specifically regarding this issue that has been going on now for over a year, and still no resolution to this reported issue. In fact, in that thread, more and more people are continuing to report this battery drainage issue, and Microsoft has not provided a sufficient resolution to it. Over the months, they have had support reps in that forum provide input, but no sufficient resolution. In fact, one person had his SP4 replaced three times, and the battery drainage issue has occurred on each replacement SP4. Microsoft has severely dropped the ball in not properly addressing this matter, and if long term reliability is a concern to anyone considering the purchase of a present or future Surface device, Microsoft's track record of very unsatisfactory support of this SP4 battery drainage issue needs to be taken into serious consideration.