How so?

Decentralization can be hidden from the user, it's an implementation detail.

There's literally a popular decentralized social network.

It's less about the tech, and more about the execution.

Historically we can look at LimeWire or PopcornTime as an example.

Both decentralized, both popular due to the ease-of-use.

what a convoluted way to say you do not agree with this. when you are dealing with people of all skill levels, every step that you put on the development process costs real money. over that, not everything is and has to be open source. we all have source code that is proprietary and has a value for us as it is. making that decentralized and private is not something easy to achieve (and I don't really see a benefit). the problem from my point of view is that we have a single player (github) that managed to attract a huge percent of the market and the competition, while it exists, it's minor.

No, it's because complexity comes with a cognitive cost, and delegating responsibility to other entities minimizes this

If you don't account for the benefit, it looks irrational, but this is true of absolutely anything