The problem with supplemental rules is that the
40k community is one that defaults to playing the "core" game and acts like supplemental rules don't exist. Just look at the old
FW debates, when it was "opponent's permission" you were wasting your money if you bought anything from
FW. It wasn't until they got rid of the permission requirement and said "

you these are part of the standard game now" that people started to accept them. Same thing with flyers/superheavies/etc, they were supplemental rules from 3rd edition to 6th edition but it was almost impossible to use them outside of Apocalypse (and hardly anyone played Apocalypse more than once a year). Now that they're in the core game they're finally relevant and you might be able to use them.