The meaning of "Social" and Success in consumer internet
1. Social = adding structure to data

If you look at the internet as a repository of data of all kinds that is constantly being generated, the "meta" meaning of what "social" networks really do, is add structure to it, Basically by allowing people do things with that data (view it, create it, tell their friends about it, tell the world about it etc) you create a sort of "tag" that says; "this is how important this data is" eg. a facebook share is more valuable than a twitter share, because there are fewer shares and they are directly to people you know. A twitter share > google +1 share, because the receivers are opt-in vs. just anyone etc, and if you look at it that way, what social has basically done is reduce an infinitely expanding world of data with static tags (defined by the creators or by the content itself) to a smaller, more slowly expansive world of data with dynamic tags (defined by the people who look at it).

Dont know how to monetize this but its just arisen as a thought: Google won because search was primary way people found things, and the internet was small enough and their algorithms were good enough that they were able to filter out the noise. The real threat to google (of fb etc) is that the internet is so large and growing so fast, and their algorithms find it so hard to keep up, that at some point people always find noise in their google search, and structured data becomes the dominant way people find things in the majority of use cases. The second order threat (this will become more apparent in the coming years) is that the layers of social and all the public stuff that people do on the web, as well as improved AI, make it easier for other companies/ideas to dominate certain verticals of discovery (the easiest example I can think of this for is Quora - it's early but you could argue they have found a better method than search for mapping and discovering "knowledge" - particularly the subjective kind)

2. Success on the web = finding the broadest single use case, and nailing the process of getting that. The path is usually by finding a series of progressively broader use cases; this is called "iterating"

This isnt really all that groundbreaking; continuing with the idea of applying web metrics to the real world to see if they pass muster (eg DAU/MAU for fridges, toilets and beds = 100%, which validates those metrics), you can argue that consumer internet success = ubiquity, and ubiquity is derived from finding a single use case that has the broadest reach (ie something that most people do every day, often a day) and nailing the way to do it on your platform (web or mobile or whatever else). So the easiest example is google; search was the primary way people discovered things 10 years ago, and google created a better way to search things than anyone else.

If you're looking for consumer internet success - perhaps you first find an activity that people do frequently, then create a better/easier/more valuable along one dimension (Eg instrumenting for better decision making or taking out a pain point) to do that activity. What this means is; if someone comes to you with an idea that sounds like 4 things, that is bad, even if the 4 things cover a lot of people/activity. If someone comes to you with an idea that sounds like 1 thing, and the one thing is highly repeatable, then the only question is; what are they paying to do that one thing today (and if they arent paying to do it, who will pay).