(please, take that in the spirit of "a little imprecision saves tons of explanation")

[1] for example we have outsourced death: killing for food, putting our relatives in graves and etcetera. This alienates us from death and gives us death anxiety when we come to this realization. And death anxiety can give us the symptoms of depression. This also makes us more guilty on how we spend this one last chance of being alive that makes us even more depressed.

There's a lot to this, multiple people have come to this idea from different angles.

Consider the baker. In times gone, he'd get his flour from the miller, he'd bake his bread in the early morning, and sell to his customers throughout the day. He would feel an important part of the community; without him, the miller would be poorer and the community would have less bread. His direct interactions with his supplier and customers would provide psychological sustenance, making him feel useful, and giving his life meaning.

Consider the (non-artisnal) baker today. He gets up early and goes into the factory where he schleps packaged inputs from the loading bay to the mixing tanks, twiddles knobs, observes and fixes things that break down in the automated sequence. And then he goes home. He doesn't meet his supplier - at best, he'll exchange a few grunts with a truck driver - and he certainly doesn't meet his customers. He might chat with his co-workers, but fundamentally he's a replaceable cog, and nobody outside the factory would notice if he was replaced. His community doesn't value him, just the product. He's a nobody.