I mostly agree with you. Mormonism is a cult, period.
Catholicism can be a cult. A cult is primarily defined by who is the prime leader or gateway to heaven/eternal life. Christianity is a cult of Jesus Christ whereby people see Jesus and His Holy Spirit as our Leader. Some Catholics see their priests or Pope as the gateway and that makes it a cult. To be fair, there are other denominations which put their church pastor or leader in the same or similar light as the Pope and that makes them a cult also.
Some other aspects of cults is extra-biblical doctrine/writings which are looked at as equal to or above the Bible. They also apply shunning to those who leave the church. Catholics and Mormons both fill those categories as well. Catholics, though aren’t universal in those aspects, but they do exist in many churches and parishes.
In the end, I know that there are some Catholics who are saved, but not because of strictly following their churches doctrine, but in fact because they ignore most of their churches doctrine. I can’t say the same is true with Mormons, because they have created a whole different thing. Catholicism at least has the basic truths in it’s cobweb of extra-Biblical practices and doctrines.
Actually, I agree with everything in your post. It’s why I said “the jury’s out” regarding Catholicism. With Mormonism it is very, VERY clear cut. With Catholicism, often I find myself saying “It depends”.