Actually I didn't quite understand this story. Something related to virtual reality (VR), or "human consciousness uploaded to a computer" kind.
As far as I could understand, it makes the argument that at a rather early stage during their development, most intelligent races develops the device of virtual realism of pleasures - kind of always in pleasant dreams! And it pretty much marks the end of development of the race - hence we have never met aliens!
Full text of this story is available online.
Reality Check, short story, review
First published: Nature magazine, 16 March 2000
This story is included in following anthologies.
- David Hartwell's "Year's Best SF 6"