In my opinion, to be truly confident that your data will be forever exclusive to yourself and people you choose is to pay for the service, to keep it running in the long run.
Otherwise, how is the service going to survive? They have to monetize somehow down the road to pay the bills.
Good point. I think it helps to learn more about the people behind the app and their motivations.
I made Handpick (http://handpick.me) as a side project and have not taken any outside investment. Hence I have no investor pressure to obtain a critical mass of users in an insane period of time.
A simple way to show that your app is going to be around for the long haul is to charge users money for it, the founder of Pinboard, a paid bookmarking web app says it best:
I asked my users whether they'd pay to support the app to run for the long haul. They love my app enough to say yes and were delighted that they could actually actively fund the operations and development.
Go on, try asking your users if they'd pay for your product. It's the best validation you can get!
To understand why the social web is so noisy, simply follow the money.
Salespeople need marketers to sell products, marketers rely on Facebook and Google to buy targeted advertising slots, who in turn optimize their social networking tools to encourage everyone to share even more, all the time.
Frictionless sharing, as Zuck puts it, because the more you share, the more keywords they can accumulate and sell as ad slots to marketers and sales people.
For the rest of us, we have our work to do and there's only a small window of our day when we're most productive.
Understand that the social web, as we know it, isn't designed in a way optimized for our productivity and happiness. It serves the tripartite of salespeople, marketers and social networking companies.
Sure it's free to use, but if you're not paying for the product, you are the product.
I've since weaned myself from Facebook for more than a year with a little tool I made that helps me, my wife, family, friends and colleagues be more selective about what they share in a attention-respectful and considerate pace.
It's called Handpick, which helps you collect links for different groups of people and send a single email digest daily or weekly, totally cutting out pesky notifications in our lives.
http://alvinlai.com/nanotate/