Giving money to any charity is potentially better for the world than giving money to
no charity. But part of the premise of this article—and of the Gates Foundation—is that some charitable acts have much higher ROI (in lives saved per dollar, or whatever other metric you might want to measure by) than others, and you should focus on those if you want your money to go furthest in doing good in the world.
This approach is usually known as "effective altruism" — there's a whole part of the blogosphere hanging off that keyword. But conveniently, I can just link to http://www.givewell.org/charities/top-charities — this is a (very well-researched) consensus list on which charities turn "dollars contributed" into "good done in the world" most effectively.
Reasonably, the entries on GiveWell's list match pretty well with the strategy of the Gates foundation (i.e. vaccines et al.) The differences in the Gates Foundation's strategy mostly come down to the fact that economies of scale for solutions work out differently when you have millions vs. billions of dollars.
Of course, you're allowed to disagree with the ranking criteria the EA people use—maybe the global number of "quality-adjusted life-years" people get to live isn't the #1 thing you care about optimizing.
But even if you disagree about the particular charities, EA—and the parent post—still have an important point you should understand: no matter the charity, contributing money is almost always higher-ROI than volunteering. (It might feel "lazy", but it's the principle of comparative advantage: the person a charity could hire for the money you can earn in time X at your job, will almost certainly do more good for them than you'd do by volunteering X hours of your own time.) And that "get the highest ROI for my charity dollar" mindset is what's important, no matter what you're measuring ROI in terms of.