So I feel that the argument you are attacking isn’t the actually correct one to attack. Though you do address (1) a bit in the post, I think it would have made more sense to make it the main focus.
This sounds like a fine topic for another post to me.
Re diminishing marginal returns, note that some of the change is Open Phil finding areas that it tentatively guesses may be higher return than GiveWell top charities. That affords room for increase in expected returns via research and allocation (I discussed the balance of improved knowledge with diminishing returns above).
For donors who were already trying to pursue low-hanging fruit in areas OpenPhil hadn’t reached, advantage has declined some, but not collapsed due to the continued presence of scale diseconomies discussed in the post (such as organizational independence and nonmonetary costs).
This sounds like a fine topic for another post to me.
Re diminishing marginal returns, note that some of the change is Open Phil finding areas that it tentatively guesses may be higher return than GiveWell top charities. That affords room for increase in expected returns via research and allocation (I discussed the balance of improved knowledge with diminishing returns above).
For donors who were already trying to pursue low-hanging fruit in areas OpenPhil hadn’t reached, advantage has declined some, but not collapsed due to the continued presence of scale diseconomies discussed in the post (such as organizational independence and nonmonetary costs).