Addiction recovery with methadone is still recovery

I’m not an addict (nor have I tried heroine) so I can’t speak to the intricacies, but I think small doses of the actual substance doesn’t create a high in perpetual users. In fact, part of the heroine addiction involves being physically ill without it. At certain doses the addict doesn’t feel ‘high’ but normal, depending upon their level of tolerance. I knew someone who used and it was incredibly difficult to see that she was using since she was functional in all aspects, but this was at low dosage. I understand that at higher doses, people can achieve a high on methadone, so are we splitting hairs?