They need to be added because they could create such beautiful doors, frames, or other designs when used with stairs and regular slabs.
Add blue and light gray dye to an Elytra and you get potential damage because it is called United Elytra Airlines. Surround one with ice and get Alaska Airlines, which when you have on Frost Walker Boots, you can create snow paths in the skies. Elytra villager too please!
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