ThMadara, Obito, Kakashi, Sasuke, Nagato all of these major characters have used power from external source, so its not a good argument to use stolen power against them
Madara- Hashirama's cell
Obito- same as above
Kakashi- Obito's sharingan
Sasuke- Itachi's Mangekyou Sharingan
Nagato- Madara's Rinnegan
However, I don't approve of jinchuriki power ups using tailed beasts as source. Now that's really cheating
Still not innate power, whether given or stolen.The power was given, not stolen.