It's unfortunate that it's being defined by the rightly controversial opinions of famous people..
To balance this article, consider checking out one of the main EA websites https://www.effectivealtruism.org/articles/introduction-to-e...
For example it indicates that longtermism is "a school of thinking within effective altruism". The popularity of such ideas will vary with time and they will be further refined with ongoing thinking & healthy debate. I for one fail to understand why it's important to maximise the number of future lives, which don't even exist - it seems very risky & unsustainable.