To be honest, I never saw how it would be "self evident" that not only there is some "objective reality" out there but that we also have an accurate representation of it. How would we know our representation is accurate? We don't have access to an objective observer, we don't even have access to a non-human observer. Immanuel Kant said, back in the 18th century, that in truth, the "laws of nature" are "laws of human perception [of nature]".
I recently wondered if the idea that our perception of reality is an accurate representation of the underlying objective reality was actually a commonly held idea around here. In Eliezer's short story "Three Worlds Collide", he has the characters say as much, because they assume that the periodic table and mathematics would be the same for every other species. But there is no reason to assume that is true.
Doesn't intent matter? I cannot control the entirety of society with my will, nor can I control what animals I unknowingly kill, but I can react to the things I know with my own actions.
It also seems irrational to let the "better be the enemy of the good". There is no rule that says that unless I solve all the problems at once, solving one problem is being hypocritical. The single decision doesn't get irrational just because I am not actually making 100% rational decisions all the time. That would only be hypocritical if I claimed that all my decisions are 100% rational when they are not.