Actually, in Version 19 (and perhaps earlier) of RSLogix 5000, the AFI is flagged as a warning. It was not in v16 (and later, perhaps).
So, at least, if there's an AFI in there, you'll know pretty quick.
Of course, for every BAD thing about them, there is a GOOD thing...at least you can (sort of) "see" what the previous programmer was trying to do...he just didn't clean it up.
Yes, the AFI detection was introduced into RSLogix5000 in Version 17. However, you have to have it enabled ....