A main point of that site is that different charities have orders of magnitude different impacts

GiveWell uses GiveDirectly's cash transfers as a benchmark and aims for at least an order of magnitude better impact:

https://www.givewell.org/how-we-work/our-criteria/cost-effec...

and there's still trillions of USD worth of real global health work to do:

https://www.givingwhatwecan.org/pledge