Jun 17, 2014 · 2 minutes

The so-called "Netflix for books" is thumbing its nose at the competition. Oyster today announced that its all-you-can-read subscription service is now on Android devices like the Amazon's Kindle Fire and Barnes & Noble's Nook HD.

Oyster says in its announcement that an Android application was the most-requested feature for its previously iOS-exclusive service. What it doesn't say is that, starting today, products made by Amazon or Barnes & Noble specifically so these companies could sell more books, will now be used to bring Oyster's streaming mentality to book reading.

Everyone with a brain and a Netflix account knows that streaming media has become more popular over the last few years. Videos can be streamed through Netflix and Hulu. Music can be streamed through Spotify, Rdio, and many other services. Companies like Sony are trying to bring a similar model to video games, and Oyster is trying to do the same for books. If these services are any indication, the idea of "owning" digital media might soon be an anachronism.

That should worry companies like Amazon, which use their digital marketplaces and physical products in tandem to create an entire ecosystem that consumers are never meant to leave. It has been busy over the last few weeks introducing new services (Prime Music) and talking up old ones (Prime Instant Video, the Amazon Appstore) to preemptively make a case for its long-expected smartphone, which in turn will be used to sell even more digital goods to its owners.

This strategy doesn't work if people rely on other services for all of their digital needs. Why sign up for Prime Instant Video if you already subscribe to Netflix and Hulu? Why listen to music with the widely-panned Prime Music service if you already use Spotify or Rdio? Why buy a book if you can download it and countless others for a flat monthly fee from Oyster? It doesn't make sense -- unless Amazon convinces consumers to keep paying for Amazon Prime.

Including digital services with a Prime membership has been Amazon's strategy so far. It's hard to justify paying $10 for a service when you can access a comparable product for free, so Amazon has been hoping that it can somehow create a system where people pay one flat fee for Prime, get free access to some content, and are then willing to pay for anything else they want.

That's a fragile foundation on which Amazon has built its digital media empire. It only works if people keep paying for Prime, are willing to deal with Amazon's clunky software, and are open to purchasing content that they can't access through their streaming services. If any one of those concessions isn't made, Amazon's services pale in comparison to others.

Companies like Netflix and Spotify and Oyster don't have that problem. They have one goal: make sure people continue to pay for their services. They don't have to sell hardware products, they aren't trying to sell digital content, and they aren't mucking around with complex systems meant to keep a dying model (selling digital content) from flat-lining and fading into oblivion.