This is what you don't seem to understand. The company that created the game...is the one that wanted the restriction.
Well, they too are wrong... or maybe they are the only one wrong, either way, I feel both "books" should be allowed.
And it will only become worse as they release more and more content this way...
Again, that's just my opinion, you don't have to like it... nor do you need to pick it apart...
I've said I'm done defending this thing now 3-4 times, yet people keep trying to tell me what certain phrases of how I've worded things are wrong.
I'm tired of this, look you all know what it is I'm after or looking for, agree with it or not, the fact of the matter is... as is, this rule has caused issues already at my table... and I expect it to only become worse down the road... for no reason what-so-ever.
It does not matter to me who came up with the rule, I feel it is wrong... it does not "add" to the game.
Thematically, if a player comes up to me and says I want to play an Air Gensai Stormlord... well, that just makes sense. And really, it's not a broken build...
We already have to know the rules from all of the books/online guides anyways, now we need to know everything from all of the source books/online guides plus what can or can not be mixed...
This is worse... and that is my opinion.
Fin.