For me, basically every other question around effective altruism is less interesting than this basic one of moral obligation. It’s fun to debate whether some people/institutions should gain or lose status, and I participate in those debates myself, but they seem less important than these basic questions of how we should live and what our ethics should be.
Prompted by this quote from Scott Alexander's recent Effective Altruism As A Tower Of Assumptions, I'm linking a couple of my old LessWrong posts that speak to "these basic questions". They were written and posted before or shortly after EA became a movement, so perhaps many in EA have never read them or heard of these arguments. (I have not seen these arguments reinvented/rediscovered by others, or effectively countered/refuted by anyone, but I'm largely ignorant of the vast academic philosophy literature, in which the same issues may have been discussed.)
The first post, Shut Up and Divide?, was written in response to Eliezer Yudkowsky's slogan of "shut up and multiply" but I think also works as a counter against Peter Singer's Drowning Child argument, which many may see as foundational to EA. (For example Scott wrote in the linked post, "To me, the core of effective altruism is the Drowning Child scenario.")
The second post, Is the potential astronomical waste in our universe too small to care about?, describes a consideration through which someone who starts out with relatively high credence in utilitarianism (or utilitarian-ish values) may nevertheless find it unwise to devote much resources to utilitarian(-like) pursuits in the universe that we find ourselves in.
To be clear, I continue to have a lot of moral uncertainty and do not consider these to be knockdown arguments against EA or against caring about astronomical waste. There are probably counterarguments to them I'm not aware of (either in the existing literature or in platonic argument space), and we are probably still ignorant of many other relevant considerations. (For one such consideration, see my Beyond Astronomical Waste.) I'm drawing attention to them because many EAs may have too much trust in the foundations of EA in part because they're not aware of these arguments.
(cross-posted)
Re: Shut Up and Divide. I haven't read the other comments here but…
For me, effective-altruism-like values are mostly second-order, in the sense that a lot of my revealed behavior shows that a lot of the time I don't want to help strangers, animals, future people, etc. But I think I "want to want to" help strangers, and sometimes the more goal-directed rational side of my brain wins out and I do the thing consistent with my second-order desires, something to help strangers at personal sacrifice to myself (though I do this less than e.g. Will MacAskill). But I don't really detect in myself a symmetrical second-order want to NOT want to help strangers. So that's one thing that "Shut up and multiply" has over "shut up and divide," at least for me.
That said, I realize now that I'm often guilty of ignoring this second-orderness when e.g. making the case for effective altruism. I will often appeal to my interlocutor's occasional desire to help strangers and suggest they generalize it, but I don't symmetrically appeal to their clearer and more common disinterest in helping strangers and suggest they generalize THAT. To be more honest and accurate while still making the case for EA, I should be appealing to their second-order desires, though of course that's a more complicated conversation.