Good morning Peter,
You make a good point about doctors and craftsmen. However, just think about how you decide which doctor to see or craftsman to employ. Usually this decision is made by asking someone whose opinion you value with regard to health or workmanship. It is a referral process based on your network, otherwise known as your community.
A few years ago, a number of sites started to pop up online where users could review restaurants, stores, craftsmen, ….doctors. People who don’t have anyone in their community who can help them form a decision will go to these sites which act as referral systems. Do these work effectively? Not really because the people posting the review are not part of the seeker’s community. The trust element is missing. As a result, certain reviewers have tried to become influencers on those sites and to increase their reach beyond the site; they became experts and made a business out of it moving to the more traditional role of reviewer but using digital tools. They became trustworthy for a community.
But let’s move beyond the personal community one can have to a more business perspective. Let’s say you build an operating system like iOS or Android, if you don’t have a community of users who will build apps that run on the OS you don’t have anything of value. Do you? Consequently, both Apple and Google invest huge amounts of money sponsoring community events where programmers can come together and discuss/learn/question all they want. In this case, it is often referred to as an “ecosystem”, which is just another name for a community. That said, these communities form around these technologies because somehow the risk associated with using them is lower. The fact that there are so many smartphones and tablets in the world certainly factor into their success because it reduces the risk of getting users to try the new app and grow the market. If you develop an app for FirefoxOS or even Blackberry it may be more of a challenge. Similarly, iOS has its own programming language whereas Android uses Java making it much faster for programmers who already have experience with Java to build apps but also making riskier because it is easier to hack.
I hope I am making my point but if not please write back and I will try to improve on my explanation. Now, I have to close this email because I have some other things to attend to.