Eh? There was no belief system behind it, no texts decreeing that it should be so, and it's not been in place that long. I suggest you read this. I think that the reasoning was it sounds like a good idea to have separate servers for Official Maps, Community Maps and Solaris arena. If you can come up with a better idea, I'm sure that the server admins would be open to changing it.
Some custom maps are quite good. I See no reason to not include ones like tc_stonerose and have a little variety.
That's what Funbocks Beta is for.
That's not reason, it's dogma.
Or, you know, you could run a server and put whatever maps you wanted on it.
Already do, thanks.
I would rather have two servers split between maps that work well for smaller and larger groups. I.e maps like stonerose are good for small to medium sized teams, but Frostbite is much larger, and works better for larger groups.
The artificial separation of official versus community maps is based on what? A belief that community maps are always beta and broken? Not as good etc? There are official maps I'd rather not play, and I'm sure they're left off of the rotation on the official server. So saying "That's what funbocks beta is for" isn't really a a reasoned argument against all community maps being on alpha etc