Heh I had almost forgotten about "mobile" and that tension. My focus was always on fighting against Pangaea, which was related, but when they folded mobile I found it to be a reasonable decision- the time had past where having a separate org just for mobile apps didn't make sense in a responsive world. I just checked and there is still a "mobile alumni" group on FB, though it hasn't been active in 2 years.
At a crude level: To compete with Amazon means running eCommerce at a loss just like Amazon do. AWS subsidizes Amazon eCommerce, brick-and-mortar subsidizes Walmart eCommerce.
It is more nuanced than that of course but at a high level that is a big challenge to profit.
RE: JK.
He surrounded himself with a handful of smart technical VPs and lots of dumb ones that he held close. The good ones eventually left and the dumb ones stayed. The replacements were a mixed bag. The tension between JK and the more successful business and technical unit (mobile) siloed under a rival executive was healthy for a while then when the axe fell on mobile, it was a disaster - lost a lot of good people.