The point being made by GP is that there are very many reasons why modern civilization on Earth may be shortlived: climate change, biological war (or lab accide

The point being made by GP is that there are very many reasons why modern civilization on Earth may be shortlived: climate change, biological war (or lab accident!), global thermonuclear war, economic failure modes, AI or AGI, large impact, etc. Fixing any one of these doesn't solve the same problem that redundancy would solve, and some of them require solving seemingly impossible coordination problems.