flashcard- V: SC: in that vs. because

[asavari]

Hi,

I was just going through the flash card downloded from this site and came across this one:
V: SC: in that vs. because

It says, in that is usually better than because.

However I remember in one of the OG11 SC #51 explainations, in that is gone out of use, it is considered stilted and ovely formal.

So can someone let me know if there is any exception to what is stated in OG11?

Thanks,
Asavari