You need to read it in the context of onion2k's original post and how onion2k's post relates to the article. There is a question of responsibility in that context, whether we like it or not.

Yes, this is a metaphor for people building algorithms (or other systems) they don't fully understand that could have poor consequences for others / society. At least, that's how I understood the relevance of the metaphor.

Criticizing "people building algorithms (or other systems) they don't fully understand that could have poor consequences for others / society" implies there is a conceivable alternative. That is it possible to build algorithms with a full understanding of all the negative consequences they could ever have for society. That seems obviously absurd to me, so the criticism is vacuous.

Er, no. The alternative is to not build those systems. Here clearly suggested is, not to let algorithms make all the decisions, but let people actively manage those funds. That might be generally less efficient (in terms of volume of trades and profit), but the assumption is that a total disaster (e.g. flash crash) wouldn't happen with "slow" humans in the loop.

How is a flash crash a "total disaster"? It seems to me that just describing it that way indicates your mind is addled by technology, since before modern times nobody would expect continuous pricing of everything every millisecond of every day or think that everything was worthless because it wasn't being quoted appropriately for an instant.