Before it
Large models were tuned for completion, not for holding a conversation.
The problem
Dialogue needs safety, factual grounding and a consistent persona, none of which come free.
What it introduced
Dialogue-specific fine-tuning with safety and groundedness objectives, plus external tool lookups for facts.
Why it matters
Google had an aligned conversational model well before ChatGPT and chose not to ship it publicly.
What modern models inherit
Safety and groundedness as explicit fine-tuning targets for chat.
What came next
Bard in 2023, then the Gemini line.