A few minutes after hitting publish, I stumbled on that post from 2022, which tackles approximately the same issues, line of thoughts, and arguments.
https://forum.effectivealtruism.org/posts/udsATFrQtc34iKs2c/doing-more-good-vs-doing-the-most-good-possible 
Let's say that mine is simply a re-release!

Thanks for those insights ! I had not really thought about "why" the situation might be as it is, focused on the question on "what" it entails. I'm really glad I posted, I feel like I feel like my understanding of the topic has progressed as much in 24 hours as it had since the beginning.

Thanks for the link ! The person who posted may not have been a newcomer to EA, but it is a perfect example of the kind of threads that I was thinking may repel newbies, or slightly discourage them to even ask.
I really agree with what you say, there really is something to dig into there.

Thanks for the answer, and for splitting the issue into several parts, it really makes some things clearer in my mind!
I'll keep thinking about it (and take a look at your posts, you seem to have spent quite some time thinking about meta EA, I realize there might be a lot of past discussions to catch up on before I start looking for a solution by myself!)