The thing is, nothing you've said is untrue for any search engine or user-driven web site. Only a reckless moron would paste code they find on Stack Overflow or Github into their project without at least looking it over. Same with code written by LLMs. The difference is, just as the LLM can write unit tests to help you deal with uncertainty, it can also cross-check the output of other LLMs.

You have to be careful when working with powerful tools. These tools are powerful enough to wreck your career as quickly as a chain saw can send you to the ER, so... have fun and be careful.

The nice thing about SO and Github is that there's little to no reason there for things to not work, at least in the context where you found the code. The steps are getting the context, assuming it's true based on various indicators (mostly reputation) and then continuing on with understanding the snippet.

But with LLMs, every word is a probability factor. Assuming the first paragraph is true has no impact on the rest.