My somewhat “cynical” answer is that an important function of charity evaluation organisations is to challenge the status quo. If everyone is funding animal shelters and you think that’s ineffective, you might as well create an organisation to redirect funding to more effective interventions. But longtermism as a field is already “owned” by EA, so EAs are unlikely to feel a need to shake up the establishment there.
My somewhat “cynical” answer is that an important function of charity evaluation organisations is to challenge the status quo. If everyone is funding animal shelters and you think that’s ineffective, you might as well create an organisation to redirect funding to more effective interventions. But longtermism as a field is already “owned” by EA, so EAs are unlikely to feel a need to shake up the establishment there.