The style is the easiest thing to catch for people; GP has said that the technical issues can be more difficult to find, especially in longer texts; there are times where it indeed are caught.

Passing even correct information through an LLM may or may not taint it; it may create sentences which on first glance are similar, but may have different, imprecise meaning - specific wording may be crucial in some cases. So if the style is under question, the content is as well. And if you can write the technically correct text at first, why would you put it through another step?