No, it isn't ridiculous. I've seen many projects available for multiple OS's that choose to advertise themselves with a Mac screenshot (or a Windows screenshot,

No, it isn't ridiculous. I've seen many projects available for multiple OS's that choose to advertise themselves with a Mac screenshot (or a Windows screenshot, or a Linux screenshot) at the top. The screenshot by itself says it runs on Macs, but doesn't establish that it's Mac-only; you need to read all the way to the bottom to make sure of that. It's disdainful of a non-Mac user; that may be accidental, but I've seen this more often on Mac product sites than on Win/Linux product sites. Your "giant ONLY ON MAC OS X disclaimer" is a strawman; what would be normal and courteous is simply mentioning that it's for OS X somewhere at the top. There are many, many product sites that do it successfully (e.g. http://www.hogbaysoftware.com/products/writeroom http://www.hogbaysoftware.com/products/writeroom). The post title on HN is a separate issue that's actually less of a problem. A random link to a product on HN doesn't carry an implicit assumption that it'll run on my OS. I don't mind clicking on it and discovering it doesn't (and besides, the author can't control the text of a link that leads to their site). But when I need to scroll down five pages on the site to ascertain I can't actually use it, that's irksome.