I've always heard and agree with the sentiment that chiptune is either a medium or an aesthetic. Similar to, but not really a genre (though I guess you could call songs composed solely with Gameboys, NESs, or what have you a "genre"), chipmusic is made with or emulating the sound, programming, etc. of old computer systems with soundchips limited in capability.
It's evoking a feeling or emotion much how classical music or rock music evoke different emotions.
I've looked at, for instance, LSDJ as the strings to the violin that is the Gameboy/GBC/GBA/AGS/DS/computer/everything else that emulates the GB's hardware or has that soundship. Obviously you could tear that argument apart and say "Well isn't Logic Pro the strings to any platform that can run it?" Yes, but it's not necessarily used to evoke the style (limited channel/voice composition), sound (simple waveforms, compressed samples, etc.), or computation (see Danimal's post) indicative of chiptunes/chipmusic, the medium, though it can be used in such a way.
You can utilize mediums with other mediums: recorded or live violin with an electronically synthesized song or backing. Music within film. LSDJ with a rock band. Percussion with guitars with basses with voice. It's a tool meant to utilize a certain sound and musical philosophy. That sound is always morphing, especially with electronic music and just most musical genres.
Take for instance dubstep. Most people would call brostep "dubstep." Is that wrong? Technically. Do they care? No. I'd classify fakebit vs. chiptune and hardware vs. software in the same struggle: Some people find the distinction important, some don't. Does that stop artists from making music and pushing the boundaries of their given medium/genre/instrument? No. Why should it stop us? This kind of discussion can be found in most musical scenes. It's the artists and groups within those scenes that tend not to get bogged down in these arguments that make innovative (maybe not "good") music.
So, I guess my answer is that it doesn't matter.