>> Another role they have is to prevent copying of content or links from one fiefdom to another.
> I have a hard time believing that considering the prevalence of the "share" button in apps.
But a "share" button in a dedicated app isn't remotely a hyperlink. A hyperlink only tells the reader about the destination, but a "share" button also tells the recipient about the source.
>> I think this idea works best with relatively young people who don't clearly understand what they're giving up when they download a proprietary app in order to read what should be a public document.
> Could you cite an example where this is really true?
Sure -- paywalls are a classic example. As soon as we accept paywalls and read articles behind paywalls, we can't share content any more. These dedicated apps are like paywalls taken to the next level.
But young, inexperienced people often don't see the problem with paywalls when compared to a public forum. The same logic applies to these dedicated apps -- they make it harder to share information. Their existence only serves the interests of the companies that create them.
> I'm just wondering what app locks out what would in another world be completely open info.
A browser gives you access to all content. A dedicated app only gives you access to that fiefdom's content. So such an app is not open in the way that a browser is, and you're limited to that app's purview.
Consider a cell phone as an more extreme example. It's a way to take conversation and make it into a product. A cell phone is sort of like one of these dedicated apps, in the sense that you can't freely move between fiefdoms -- and if you try, you have to pay "roaming charges".
The global issue is the commoditization of information -- turning information into property, into a commodity. The idea is to take a public forum like the Web, privatize it, and sell it back to what are now captive information consumers.