Comment by ChocolateGod

Density (and wavelength), rather than total power, is important.

Sun's 1kW/m^2, and even then you shouldn't look directly at it, and being out in it all day without protection leads to sunburn.

Last time I forgot sunscreen at a UV index of 10 my skin started peeling of after half an hour so...

It’s not, for an extended period of time. Now imagine it was collimated rather than diffuse.

So there's this thing called sunburn...