This article sets my teeth on edge the same way your talk at Webstock did. The reason for this is that you present it as if this is a new problem that has only occurred because of developers and techies in the last ten years. You never used the term ‘monopoly’ as this is what these fake markets are. Also you gloss over the concept of of anti-competitive practices such as using unsustainable pricing to get rid of competitors.
These problems have been around for a long time and are well understood such as supermarkets which can control the prices they charge customers and the prices they charge suppliers, this is most prevalent when selling and buying produce.
These anti-competitive practices are best tackled by confronting the business models that are trying to create the monopolies and this often can only be done by regulation to ensure that smaller competitors can compete fairly. If an individual wanted to have an impact they should engage in the democratic process and engage in lobbying/activism to make these issues known and dealt with. A person acting as a citizen is going to achieve more impact than a person acting as a developer.