Then make the paper out of hemp.

Yes, sigh, the "Save the trees argument" it never did make much sense. first and most important. trees are a renewable resource. second, the best trees for paper are from small farmed trees. not old growth forest.

The actual take away should have been, the bigger the paper industry, the more trees there will be.

If you are grasping you can bring modern carbon sequester theory into the argument. but I will admit that is too complicated a subject for me to feel comfortable leaning on it.

I feel like humans have trouble with the concept that the environment is not just one single thing, and that something can be good in one way but bad in another.

Its kind of like all those wine is good for you vs bad for you studies where both are kind of correct but in different ways.

Assume I get 4 reuses out of a paper bag, and I use 4 bags per week. I don’t think I could replace 4 bags worth of paper per month that I would have bought otherwise.

True, but recycling takes water and energy. You’d probably still going to have to use them yourself a fair few times to make it a net positive.