I don't think Jetpens makes any pens themselves, although they are a retailer and sell all of these pens so it's definitely advertising. However, Jetpens in gen

I don't think Jetpens makes any pens themselves, although they are a retailer and sell all of these pens so it's definitely advertising. However, Jetpens in generally reputable and their recommendations are generally good. HN typically likes posts about tools, so it's not too surprising a good tool recommendation post is popular here