The Pythia was sacred, the Pythia was touched by the divine, the Pythia spent days hallucinating under the influence of burned leaves and natural gas.
The ancient Greeks took their land from a people who regarded snakes as sacred, at least sometimes. They also believed women could be sacred, at least sometimes.
The ancient Greeks had no particular feelings about snakes. And they certainly didn't regard women as divine-- women were the babymaking home appliance centers of their world! But when they found the seat of the Delphic Oracle, they knew there was strong magic at work. It's best not to mess with that stuff. So they redubbed it after Apollo, slapped some bay leaves on the proceedings, and left a woman, the Pythia, to interpret the oracle.
This was not fun for her, and she was still a woman, so they also left some men to interpret her.
Being touched by the divine is rarely *fun*.