It seems we're getting bogged down by conflating decentralization with democratization. Email is certainly decentralized but its not something every layperson can run and maintain.
Even true democratization generally still only serves to multiply starting advantages unfortunately. Give a laptop to a 12 y/o upper middle class kid in a healthy home, and you could make the next Zuckerberg. Give one to a poor kid in the ghetto with a violent home life, and you make get some improvements, but the net effect will be widening inequality. This is why redistributive policies are always going to be requi…
I'm not quite sure I get your example: so if you give it to the former you're more likely to produce closer to the extremely rich man with the socially corrosive advertising platform that has clear, real, marked destructive effects on entire country's political structures, the one that vapourised entire media businesses due to misinterpreted analytics, etc etc. The net negative effect of the hypothetical latter seems vastly less?