I was replying to this bit in the post:

The problem of counterfactuals is the problem what we do and should mean when we we discuss what “would” have happened, “if” something impossible had happened

...and this bit:

Recall that we seem to need counterfactuals in order to build agents that do useful decision theory -- we need to build agents that can think about the consequences of each of their “possible actions”, and can choose the action with best expected-consequences. So we need to know how to compute those counterfactuals.

It is true that agents do sometimes calculate what would have happened if something in the past had happened a different way - e.g. to help analyse the worth of their decision retrospectively. That is probably not too common, though.