In the ancient times Gallifrey possessed a massive empire. But our influence over these worlds did not always result in a positive outcome for them. [Narvin is good at understatement. Ancient Gallifreyans were terrible people.]

Lord Rassilon instituted the non-intervention policy to protect the peoples of the universe and the integrity of the web of time. If we gave Earth advanced technology, why not Antari Three? Why not Indra? Krontep? And if they misused that technology and destroyed themselves in the process, did we want to be responsible for their extinction? It was safer not to go down that slippery slope at all.