War Banner and Font of Rage

I was suprised to learn that War Banner/banners can't be supported by Font of Rage/Fonts.

The Flavour Text of Font of Rage states "Support Skills which create stationary objects". This is literally what the banner is, no? So why are they not compatible? I think they should

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Same. As objects go in this game they dont get much more stationary than a banner. Bought the banner armour and everything...