At it's core, I struggle to see how anyone can disagree with effective altruism as a basic principle. People want to do good in the world, but we're all monkey-brained and emotional, so that often manifests in ineffective use of time and resources to do things that give an immediate, visible outcome so we can feel good instead of what would actually do the most good.
EA to me is basically just shifting altruistic desires from emotional-payoff (volunteering at a soup kitchen around the holidays, donating to a local animal shelter) to things that have the best outcome (volunteering at a political action group to improve laws, donating to an NGO distributing mosquito nets in malaria zones).