We might have in mind the kinds of holograms we can buy in a toy store or whatever that we're clearly constructed by somebody. There's very good reasons to believe that some kind of holographic behavior is part of our best understanding of quantum gravity. I personally always struggle with the general two-dimensional diagram of gravity, the standard bowling ball and a trampoline image ingrained in most schoolbooks and online. If you layer in 4D space time and how gravity acts upon it, it gets even harder to explain in words. So I'm not really liking the expanding balloon analogy for the universe but I see why you want to use it as long as you're super clear about its limitations