AI already works, but only in some areas like factory management, financials, medical, and ads.
Depends on what you mean by AI. If you mean specialized trained models that do very specific things (e.g. optimizing just-in-time component purchases or using computer vision to make robots work more effectively, making stock picks, spotting tumors on scans, and optimizing ad spend to get the best results), then yes. If you mean LLMs, I think you missed the mark with your list (except maybe ad creation; that's plausible).
LLMs are great for automating trivial work as long as there's no high financial cost for mistakes. Chat bots to help you search for products on a website better are a great example. Or LLMs to help you write the skeleton for new code or help you write unit tests (as long as you check the results). Or LLMs to help you look for bugs in code or review code before submission. Or LLMs to help you create prototypes of new software while deciding what approach you want to take. Or LLMs to quickly create artwork for fun, where you don't care if there are extra fingers.
LLMs are not great when there is high risk. Chat bots for airline customer service are a great example. Turning LLMs loose writing code without a competent programmer looking over its shoulder is another good example.
In between are the use cases where it functions adequately, but may not save much time, because the overhead of reviewing its work adequately is a sizable percentage of the time required to do the work by hand. Writing real-world production code is a great example.
Presumably it will get better over time. But whether it will ever reach a level of trust where we can turn it loose to write code and not carefully scrutinize that work, I couldn't say. Right now, there's too much risk of it saying that tests pass when they actually haven't been run, or worse, when the AI has decided to delete the tests so that they won't fail. There's too much risk of gaslighting across the board. There's too much risk of AI subtly misinterpreting prompts in extremely creative ways to give you results that look like they are correct but are actually wrong. And so on.
I'm going to assume for the moment that the C-suite at Meta are not complete and utter morons. So from this, we can conclude that Meta is firing people not because they actually believe AI will do their jobs, but rather because they don't have enough revenue to pay for their AI hardware costs, and they're hoping that they can get away with counting on their near-monopoly on social media to let them safely unstaff large parts of Facebook, Instagram, and other services in the short term so that they can build their data centers.
And while that might be true (because the DOJ let Facebook get way, way too big), that's a stock price disaster waiting to happen. It's risking throwing away the whole company to spend more money on Facebook's LLM technology, which might still never be good enough for them to actually make money at it. It made sense to do that work up to a point, because they could benefit from it internally for things like abuse detection. But trying to productize it without adequate rounds of funding is a mistake. If they truly think their tech is up to snuff, they should spin it off into a separate subsidiary and do rounds of financing to pay for the cost, with separate stock offerings.