Well, the first three you mentioned are for providing power to other chips, the last 4 are RF amplifiers, they aren't really related.
Why you need (or want) multiple power management ICs: they are likely powering separate zones of the board which may have very different power requirements, e.g. need different voltages, need to be able to power up or down separately, or need particularly clean power.
Why you need multiple RF amplifiers: Almost all phone today run on many different cellular frequencies and protocols, a quick look at the specs indicates the iPhone 6 supports: 800Mhz, 850Mhz, 900Mhz, 1700Mhz, 1800Mhz, 1900Mhz, 2000Mhz, and 2100Mhz along with various different signaling schemes. You can't handle all that in a single RF pathway.
> But it's worth remembering that Spotify's fundamental unit is the user playlist
I don't think that is true.
My interaction with Spotify is much more about listening to an artist or song and using 'more like this'. And the fundamental unit of sharing is 'friend x listened to this song'. If I know I like their tastes I tend to list to that song then, if I like it, listen to 'more like this'.
I spent about an hour earlier trying to use Apple Music via iTunes and left incredibly frustrated. I couldn't make it do anything I actually wanted it to do.
As a simple example, go to 'new' then, pick a genre from the incredibly awkwardly placed drop down, scroll down and you see 'top songs'. Cool, I thought, lets play the top songs from this genre! Except, as near as I can tell, there is actually no way to play those songs as a 'playlist'. You can click one at a time, and they play, but after each finishes it just stops.
Weird for me it seems exactly right. I tend to share and follow playlists not individual songs.
Also I have had no issue getting Apple Music to work the way I want including what you were trying to achieve. I just clicked on Top Songs and it opened as a playlist where after the first song finished it played the next one. Maybe you were clicking the indvidiual songs ?
This is all in window at the default 'theater mode' size of youtube. I can't full screen either of the VP9 options without completely maxing out the CPU, dropping frames and during my laptop into a frying pan. Its really hot even in window with chrome VP9 using ~175% CPU.
Glad to see some hard numbers on Chrome video performance compared to Safari. I like Chrome because I like the integration with Google services and separate user profiles so I have 2 sessions going at once, but I often have to take Hangout meetings in Safari because Safari doesn't turn my laptop into a hairdryer heating element.
I am curious, though, do the Chrome devs have access to the video APIs that the Safari people would?
There is no reason for h264 decode to take much power at all, it's all done in hardware now (or should be done in hardware).
In other words, Safari's power number isn't surprising but I don't know how chrome manages to use so much processing power. Even my cell phone can decode 1080p60 without catching fire but chrome manages to bring a $2200 laptop to it's knees doing it.
I wouldn't be at all surprised that it would light up with the phone off too, or really with any metal material set on it. You've got a free antenna set above an already noisy circuit: the Arduino plugged into a laptop via USB. Putting a metal cover over the antenna could easily be enough to increase the field strength.