Chaim Berlin had some internal conflict. They allowed the Rosh Yeshiva to maintain full control over the yeshiva. The Rebbe had a hand in the settlement. I’m assuming you know the Torah VDaas story.
Nobody is putting the Chabad Rebbe on the level of Rav SF”M in spreading Torah. But the scale of the Rebbe activities, is very impressive. Unlike today, the major yeshivos felt it their obligation to spread Torah all over the world. Where they missed, the Rebbe had someone there. Plus he was the only one who was building Torah behind the Iron Curtain?