Blueprints Required for Promoted Church

I don't know if this has been brought up before, but why is it we need blueprints to level up our promoted churches? 

We need at least one for level 19 and two for level 20.  This is the only promoted building that we need blueprints for that I can see and it has to be maxed out to reach hero level 50.

If you are saying that regular church does not require blueprints, but promoted one requires them, then it is a bug. If you are wondering why it requires blueprints at all, then why not? They provide you access to 2 final hero levels which is not that big of a deal if you can't reach it right away. Hero level 48 is not that much weaker than hero level 50, so it is not critical.

no it's not a bug, which is why I did not put it in bug reports.  I was just curious as to the reasoning, though I figured it is this way for the reason stated.  I just wanted to make sure I was not missing something.  :-)