Because the population of Hackernews has a great overlap with the population of Silicon Valley-type software developers and Redditors, who vehemently believe feminism is the same as egalitarianism and believe the few books written by a few big figures make up for the fact feminism contradicts those words at every corner in all of its actions. And when you point that out, the first thing you get is a No True Scotsman claiming "that's not real feminism / not all feminists", despite the argument being that feminism as a whole doesn't seem to care for men beyond empty platitudes and words.

It is literally in the name. FEMinism. If it was truly "for both sexes", we could argue the naming is sexist and supremacist. We already have a better word, egalitarianism, and people still aren't willing to adopt it.

Notice people talk past my example as well. I'm explicitly asking if feminism would prefer resolving an issue which prefers women over men, over an issue which benefits women more but benefits men equally. How this simple question cannot be answered by proponents of a movement this big, is possibly the biggest red flag. Yet we see it in the media every day: some minor issue with women needs major attention, despite there being an egalitarian issue which would help anyone outside the upper class way more. If lamenting about some "pink tax" is more important than resolving a mental health epidemic caused by making people increasingly more competitive with one another, where failure is met with lasting mental trauma, surely that should tell people what feminism really is about.

The very people claiming to be proponents for men in their words alone, are the ones partially responsible for the mess. And they are too blind to see it.