Scale corrupts. And absolute scale corrupts absolutely.
Software systems are created iteratively to grow, adapt and evolve over time. At first, the team focuses on attracting a small niche of users, and on developing a small collection of complimentary features to "solve" a "problem".
With phones as interfaces into a planetary computer, a simple app or website can grow, adapt, and evolve itself: the one, small niche becomes several. And eventually millions. The small collection of features proliferates into an overgrown network of them - each trying to maintain a balance of functionality, consistency, interoperability, and security.
As the simple software system scales, it interfaces & influences with more of the world's complex systems. And, soon, it becomes a complex system itself. With each new culture it comes into contact with, and each new feature introduced, the points of possible failure and manipulation increase exponentially. The system simply lacks the flexibility to adapt to the needs of the many, so it prioritizes the needs of the few.
What began as a local experiment from a trio of co-founders soon scales out of control. For while we have perfected the art of scaling our technologies, we have neglected the art and grace of designing and guiding them to "egalitarian ends" (h/t ed).