Once you manage to sit through the tame, these things can be absolutely amazing for gathering berries.
You'll need two people, a quetzal, and your shiny new stego.
Have one person on the quetz, one on the stego, and have the quetzal pick up the stego in its big chicken feet.
The quetz may now fly around, very close to the ground, and the stego can swing to get constant berries.
Don't spam the "swing" button, or you won't gather anything. Wait until the swing animation is over, and then tap it again.
When the quetzal is encumbered, they can drop the stego to regain stamina, the person on the stego can drop the undesired goodies, and you can go off again.
I have a stegosaurus called Strega and she’s a GOD, can kill five giant beavers in a few swings, has very high health, doses decent damage, and helped me and my only tribe mate, my dad to tame our first giant beaver.
They’re great adventuring dinos because Raptors and Kapros can’t knock you off, and they collect tons of berries and thatch. I used mine to collect rare mushrooms and rare flowers in the swamp. Her name is Giratina. She’s awesome.
If you don’t want to run around gathering fiber and wood to quickly build a base last moment before the Allosaurus pack nearby spots you, if you want to tame Argies quickly and effectively, if you want to take out raptor packs quickly, you will need a stegosaurus.