The basic issue is lock-in. Ideally we'd have no lock-in, but that's a benefit balanced against other benefits (e.g. having a good UI, ease of setup and maintenance, enough scope for vendors to make money and stay in business). In practice this means we tolerate a certain amount of lock-in for other benefits.
But, the problem comes when everyone thinks that they can be the guy with the tolerable lock-in. Use MY video service -- anywhere, MY platform -- running on anything, MY app store -- on anyone.
Amazon's model is illustrative. It's hard to read non-Amazon content on a Kindle (harder than any other platform!) but easy to read Amazon content on any rival platform. They've been less successful with video because they aren't able to leverage their existing near-monopolies as well.
Google Play Books lets you upload epubs, PDFs, etc. and syncs them for you between your devices. I don't know if that meets your needs. I use it for all the papers I want to read on my tablet.
But, the problem comes when everyone thinks that they can be the guy with the tolerable lock-in. Use MY video service -- anywhere, MY platform -- running on anything, MY app store -- on anyone.
Amazon's model is illustrative. It's hard to read non-Amazon content on a Kindle (harder than any other platform!) but easy to read Amazon content on any rival platform. They've been less successful with video because they aren't able to leverage their existing near-monopolies as well.