That's not really true - the current generation, as in "of the last three months", uses reinforcement learning to synthesize new training data for themselves: https://huggingface.co/deepseek-ai/DeepSeek-R1-Zero
Right but that's kind of the point: there's no way forward which could benefit from "moar data". In fact it's weird we need so much data now - i.e. my son in learning to talk hardly needs to have read the complete works of Shakespeare.
If it's possible to produce intelligence from just ingesting text, then current tech companies have all the data they need from their initial scrapes of the internet. They don't need more. That's different to keeping models up to date on current affairs.
It worked well for the Habsburg family; what could go wrong?