It’s a thought experiment that gets to the core of why fundamentalist utilitarianism (like you’ll often find in SV rationalist communities, especially AI fanatics) is an unbalanced approach to morals and ethics.
Utilitarians can declare that they believe that there is a proverbial universal panacea, and then work backwards to justify within their moral framework literally any action that they take that could be construed as work towards that panacea.
But what if no matter how much effort they put into achieving that panacea, they never make meaningful progress? And all the while they’ve massively increased the amount of suffering that people who they are surrounded by?
As an absurd example, imagine a utilitarian who’s convinced that if we sacrifice infants to the Gods that we’ll get to an AI singularity faster.