I don't see an issue with creating multiple accounts as long as they're not used for abuse, e.g. spam or trolling, or cause technical issues, e.g. creating millions of accounts. I mean if done right you'd never know or care.
> Please don't use HN primarily for promotion. It's ok to post your own stuff occasionally, but the primary use of the site should be for curiosity.
Promoting your app in every single otherwise okay comment is certainly distasteful.
Today I'm using it as a concrete example of H.265 (BPG) as an astonishingly good alternative to JPEG in applications where you control the encoder and decoder.
I think that's about the best you can do not to promote your product while trying to give real-world examples of things that are being discussed.