Google still almost always gives me what I want but when they "improve" my results by excluding words for me it ALWAYS fails. This morning I went looking for an Ansible role and the first few results it "helpfully" excluded the word ANSIBLE for me. I see this behavior quite often and I really do not understand it.
The way I see it is that Google is getting closer and closer to showing you only what they want... They tell you that they are guessing what you meant so that if it is completely unrelated, you don't get too suspicious.
Or maybe they are showing you what most people want, on the grounds that most people search for the same stuff.
In the context of billions of users doing billions of searches, HN readers could be fairly extreme outliers...