There's nothing wrong with not knowing what ACH is and asking about it. But conversely, there's also nothing wrong with writing an article about ACH that doesn't bother to explain the background in detail, nor is there anything wrong with posting such an article to HN.
The only thing I take issue with is the suggestion that it's somehow unusual or noteworthy.
> In the future, you could just answer the question, or you could opt out of replying entirely.
I noticed that other commenters had already answered the question adequately, or else I would have included it in my response.
(For what it's worth, I just tried a Google search for "ach" in an incognito window with both region and language set to Germany, and two articles about the ACH system were on the first page of results. Again, I am not saying this to criticize for not knowing about it.)
