So i do not see any reason now why this is not allowed unless its for exploitation reasons that are unknown to me. I had thought it was like this to prevent someone from storing said ores with a silk touch and then using a fortune pick on them later. But apparently this is exactly what u have to do after having an admin place them? unless maybe for obvious decoration purposes. I would love to be able to place them myself for a variety of reasons, from traps/hidden doors. to creating natural looking areas underground. Having to get an admin to place them is a major inconvenience.
Is there something buggy with McMMO that gives you experience on placed ores, because I could've sword any placed block doesn't give xp. Maybe just see if the developer comes out with a fix first.
Ah, so all it does is say "Someone placed stone at x, y, z, so don't give xp for mining it" Dammit people, this is why we can't have nice things