It's true that I don't respond to every candidate, but I also never promised to. I DO read every single resume sent to me, guaranteed. Normally I just only reach out to people that I think are a good fit for us. I end up responding to at least a dozen candidates for each HN posting. Please keep in mind there is no automation here, and no recruiters - it's just me, and I have to balance running a company.
That said, you are 100% right that I should send at least some response to everyone, even people we aren't going to move forward with. I'm working on a process for this and will start doing it soon.
In the meantime, I want to personally apologize if you feel I wasted your time. If you want to send me a note via email I'm happy to give you some individual feedback on your application and why we didn't feel it was a good fit.