Section 300 IPC: The Abettor Conundrum

I'm reading Section 300 for the umpteenth time and I just can't wrap my head around the 'abetting' part. If a person abets a murder, but the abetment itself doesn't lead to the death, they can still be charged under 300. That's fine. But what if the 'murder' was actually culpable homicide not amounting to murder (Section 304)? Suddenly, the abettor's liability is reduced to 304 even if they played an equal role in the crime. Isn't this inconsistent? Shouldn't the abettor be penalized equally if they were instrumental in causing the death? It's weird how the same act can attract different punishment depending on who's being prosecuted - the principal perpetrator or their 'abetter'.