Presumably this sort of thing was rampant pre-internet? News outlets would _have_ to receive embargoed information so that they could publish papers on time. I believe government budgets are a good example of this happening. I think the weird shift was when online journalism started, and live reactions became the norm, no?

Or you could wait a day or two to write about it, but with initial reactions etc. added. 24-hour new cycle came into view in 80s I think?

No, embargoed news is super common. Almost every single product announcement goes through that. Critics watch movies early, companies have access to LLM model improvements early, car manufacturers send production models early… it happens everywhere all the time.