Ferritic stainless steel "typically" contains lead as well...
The key here really isn't the generic type of metal (brass, stainless, etc..), its buying from someone who can tell you precisely what metals are being used and what their makeup is should you want to know.. Simply stating stainless doesn't necessarily mean lead free either.
My bigger concern regarding the particular item that spurred this conversation is not that it is made of brass, but that the maker either would not share, or simply did not have information to share regarding the make-up of the metal being usedl.
I would have absolutely no concern using an all brass genesis atty & drip tip, assuming the maker can share appropriate details, and I believe that specific type of metal is safe to use. There are several grades of brass I'd have absolutely no concerns with, personally.
I agree, and something that a lot of people either don't realize or don't care about, is brass unlike say ss not only has the lead that might happen naturally, but they add lead to it to make it easier to shape. And as far as the well people have been using it for hundreds of years, the added lead has only been started within our lifetimes.