GPT-3 will reduce the premium on style compared to substance.
You can make GPT-3 affect any writing style. But you can't make it actually have something to say. That feeling - of reading something that's wasting my time, because it doesn't actually have anything to say - is not going to go away just because what I'm reading says "dang" every so often.
These articles may have substance, but simply be far from the best presentation of that substance. I think GPT-3 and similar projects will do a fine job at subpar regurgitation of existing info that's better covered elsewhere but still manages to capture eyeballs, which describes, I expect, something like 99% of all writing on the Web, including, and perhaps especially, message board posts like this, as people often remark when yet another 300-post thread hits the front page on [some tired topic the discussion of which plays out the same every time]. Long-form print isn't perfect but is somewhat better, since there are some barriers both to publishing and to reading and you're not giving the writing away for free so simply holding a passing reader's interest for two minutes means nothing. The web, though, and maybe even magazines? I wouldn't bet against machines doing much or even most of that writing within a decade. Consider: how much of an issue of, say, Cosmo consists of light re-workings of earlier, recurring articles? People already joke about that kind of thing. Machines can probably do that work, very soon.
GPT will serve as intellectual humiliation. Some people will be embarrassed to find out that most of their reading materials can be generated by robots. On the margins, that can lead to people deliberately seeking out more intellectual content. That includes long format materials such as books. On the labor side, writing talent will be allocated away from shallow topics. That's a plus to me.
Seems like all GPT can produce is an infinite supply of shaggy dog stories. I don't know if I'd call that intellectual humiliation, just a lack of a point or punchline.
If GPT produces better output and is carefully mixed in with existing stories, I don't think anyone will notice.
What percentage of stock price stories are generated by a bot? Off the cuff and totally guessing, I'd say 50%. Do you know the exact number? Could you tell? Would the headline service tell you? (probably not)
As for the stories that merely describe stock movements without any real analysis, I myself would read those. I'm completely fine with that as long as there's reliable QA on the output.