Question regarding Inbox subfolders

[Vlip3]

This is not really an issue but rather a question. I've noticed this with ALL ROMS I've flashed (including stock) so I don't think it has anything to do with the ROM but maybe one of you gurus can explain it to me.
I have gmail and I've created filters with labels so I can more quickly access my e-mail messages. On my TP, when I select the e-mail tab (TF3D) and press the Inbox button, I get a list of all my messages that are in my inbox. If I touch the drop-down arrow next to "Inbox" at the top left, I get a list of subfolders with names that correspond to the gmail filters but they are all empty. All my messages always wind up in my Inbox folder.
The question is, if these folders are created by Outlook mobile, why doesn't it put the messages into these folders and if it isn't going to put the messages into these folders, why bother creating them.

Thanks!
Vlip3