Rav Avigdor Miller single handed took a MO Young Israel and turned it in to a Charadi Bais Medrash. He taught people with no learning experience gemarah and went through Shas with them. He was a writer an orator lecturing to the public. He was to those who knew him Daas Torah and one of the last European Educated Great Rabbis.
Comparing R’ Avigdor Miller to Rav Moshe is like comparing a sniper to a machine gunner. Which is why Rav Moshe when asked about smoking said Hashem watches out for the fool meaning it’s not prohibited to smoke. This is because R’ Moshe felt the smoker would have a hard time breaking the smoking habit. While R’ Avigdor Miller saw the threat that divorce posed to the Jewish community and fought against it. What you are seeing is from his speeches which was made for the masses. If you spoke to him about a case where the husband is withholding a get when there is no chance of reconciliation, just out of spite, he would probably tell you the man isn’t human and the get should be given.