It matters, sure, especially if there are great alternatives handy that really do spend much less resources for much more benefit AND working on the example at

It matters, sure, especially if there are great alternatives handy that really do spend much less resources for much more benefit AND working on the example at hand rules out alternatives. But without those qualifiers, it is a weak line of reasoning. It's pretty rare that we can attack a social problem only one way at a time. Is it a reasonable argument to say that the USA's carbon emissions do not need to be worried about, because the USA does not emit more carbon than anyone else? China produces about 40% more carbon than the USA.