I know that's what the wiki says but I tested it myself and had no issues with it.
I don't even understand what limitations it is 😅
The only thing that differs will be the way the model will be loaded and therefore displayed depending on where you look due to Minecraft mechanics
For exemple this test desk has item_frame entity
And the hitbox config ;
hitbox:
height: 1
lenght: 1
width: 2
width_offset: -0.5
If you want really use armor_stand, you can rework the display yourself by opening your counter json file (make a copy just in case) in blockbench and following this steps :
https://itemsadder.devs.beer/plugin-usage/adding-content/furniture/creating-a-furniture