Wow, barbaric... that is pretty strong word... I only come to hear about tank cycling first time in my 30s and that was just this few days. I could agree to very old school. Even today, I see fish stores here in my country cycling new tanks with beta and other small fishes inside too. It seems pretty common in my country. Never heard it was such a bad thing or was it just extreme or exaggeration? Plus, those fishes that my family had taken care of (big and small fishes like Arowana, Koi, Toman, guppies, beta etc.) they never died without waiting a tank cycled. I am not sure how to tell about whether they are teens or not but they sure look adults to me. Our fishes have lived with us for at least 5 years or more before giving it away.
Btw, I use API Stress Zyme.