Yes! Thank you so much then! ;)
That rule is semi-standard or at least for me. The reason for that rule is because there are people that distribute hacked Pokemon as legit Pokemon (intended or not. Not talking about members of PC). They bred illegal DWF Pokemon, thus the offspring will appear as legit.
Note that: One can still create a legit-looking Pokemon that was caught from EF or HG,
but Pokecheck can trace most of these illegals.