I don't understand where you acquired this view of economists. I am an economist and I assure you economists don't ascribe to the "measured GDP is everything" view you attribute to them.

This absurdity reveals itself when you see economists scratching their heads, thinking how we can get people to spend more than they want to, in order to help the economy. Unpack those terms: they want people to hurt themselves, in order to hurt less.

This is not an accurate portrayal of what Keynesians believe. The Keynesian theory of depressions and recessions is that excessive pessimism leads people to avoid investing or starting businesses, which lowers economic activity further, which promotes more pessimism, and so on.

The goal of stimulus is effectively to trick people into thinking the economy is better than it is, which then becomes a self-fulfilling prophesy; low quality spending by government drives high quality spending by the private sector.

If you wish to be sceptical of this story (I'm fairly dubious about it myself), then fine, but Keynesians aren't arguing what you think they're arguing.