If it's any consolation, I feel like I've been pitched 10 different versions of this product over the years and I've encountered a lot of startups trying to do the exact same thing. You probably didn't get any YC traction because they'd seen the same thing so many times before. I wouldn't be surprised if we could find a YC batch or two that already contained this exact idea.
Thanks, and this might be it - it's even more obvious than I ever realised!