That is not entirely accurate, as I understand it. But hey, I've certainly been wrong before.
In my experience, if you submit a letter to the Agent, granting them the right to represent and file forms on your behalf, with your girlfriend as your sponsor, if she would be deemed an eligible sponsor, after going through the online Sponsor Registration Application process. BUT, if she has been through the online registration process, and already received an email stating that her online sign-up application has been accepted? Then you could submit the application for an eVisa through the online application process, without having to pay the typically overpriced fees of an Agent. Before an application will be considered, a nonrefundable fee of 2 juta needs to be paid.
Should you choose to use the VOA, you MAY be able to convert it to an ITAS, KITAS, then KITAP, but I am not SURE about that. Research VOA and see if there might be stipulations about those issues. I just searched on the Imiggration website, but I ouldn't find anything relating to such a gambit.
Good luck.
GOOD IDEA! Check with your local Embassy, hopefully the information will be accurate, and it will certainly be less annoying than trying to use the online chat bot.