That seems true for most things EAs fund apart from direct service delivery interventions such as distributing malaria nets.
I.e. it is a valid consideration but it is not a justification to work on surgical instead of systemic interventions in areas where all interventions are operating uncertainly over multi-year indirect theories of change (the majority of what EAs do outside GiveWell-style GHD work).
I’ve now tried to clarify what I mean in my post, Nick.
I agree with you that concrete suggestions are lacking, my claim is that this is—at least partially—due to too little effort on this angle and that this seems worth re-examining in a change of rapid and profound system-level changes.