The game already takes into account realm-preferences though. You can hand out more medals to non-realmmates than you can to realmmates.
The fact that it's easier doesn't mean that it is done more.
I have always given more models to realm mates, for the simple fact that these are the people I play with the most.
While it might be due to my misunderstanding of the system, I'm also less prone to give to foreigners unless they really remarkably deserve it, because I know it may then hinder my possibilities to give to a realm mate when I find he deserves one too (whereas if you can give to a realm mate, you feel safer in doing so because you know you will always have the option to give to a non-realm mate after). Against, this might be because of my misunderstanding of how medals worked, but I always felt incited to hoard my medals enough to always be able to give to realm mates, so as to not feel limited in my options when deserving people show up.
Also, I could guess with pretty good levels of certainty most of where my medals came from. And it was pretty much mostly from realm mates.