Pardon my being blunt, but you don't know what the heck you are talking about. I happen to be born and raised a Catholic and the Scriptures are very revered among my family and my parish. I know many Catholics that know Scripture better than Protestants.
I serioulsy doubt that many folks argue about the points of free will versus predestination anymore. It's rather esoteric to most folks. Perhaps your world is more erudite than most.
You made my argument yourself. Most Catholics DON'T emphasize Bible study. So, it would be hard to have arguments with the predestination folks when Catholics simply don't really care about the argument any more.
Perhaps there are arguments between Protestants but, I don't know about that too much, as I don't care either.
Also, that most Catholics don't even engage in the free will versus predestination argument shows that THEY, at least, know Church doctrine about that one subject. I knew about it LONG ago and I have never heard it discussed in sermon. Why discuss such an antiquated, moot point?
As for Catholics being less well-versed, lol, that's a rather snide thing to say. You couched it but it's simply telling me that, in your opinion, we are ignorant about Church doctrine. I wonder how you would be able to generalize about all 1 billion Catholics.
If Catholics go to Mass and listen to the sermons, they DO hear about doctrine. I wonder why you think they don't. Perhaps it's just your own peculiar bias. It's very odd and saddening to hear such stereotyping.