Hey, I love fantasy & sci-fi as much as the next guy -- Disney World, Harry Potter, Lord of the Rings, Guardians of the Galaxy, all wonderful stuff, not a word of it true.
So what you're talking here is not "science heresy", it's not science period, it's make-believe fantasy.
Totally, nothing wrong with make-believe, just so long as you don't pretend it's real science.
So, you've read something suggesting these super-sized sauropods were "to big to walk on land"?
That's fine, now I'm suggesting a real science book (post #33) which will set your mind at ease on this subject.
The Cajun: "I remember, way back when in school, where we were taught dinosaurs like the Brachiosaurus were the biggest land dinosaurs that could exist and they also had to live in swampy areas where water would help support their tremendous weight."
Sure, and nothing today suggests those beasts did not live near rivers & lakes, but it also seems that some of them travelled overland, perhaps migrating in herds, and if you wish to learn the whole debate, then I suggest the book above.