Albeit I can't disagree with your point. There seems to be significant evidence to support the hypothesis that a minimal degree of socialising helps prevent mental decline.

For instance consider the different things you need to consider whilst holding a simple conversation. It's not the same as talking to a wall. It's a game with constraints and a game that our DNA would rather have us do in order to better our chances of survival through cooperation with other members.

Alone is a televised contest, not a "reality show" as we've come to know them, so your comment does not apply.

The contestants (especially those who make it to later stages) are highly-skilled survivalists.

still feel like a reality show to me.

and talking to a camera and pointing a camera to myself most of the day without even a mirror or comb nearby would make me double anxious.