It's easier to hide bad writing with more difficult words. When writing in a way that's easily understandable, bad writing or arguments that don't make sense become much more evident.

I see it as a progression. It's easy to lie to yourself and think you're a good writer by clouding your prose with difficult-to-understand sentences.

I think once you've mastered writing simply, you can be confident that you're able to move on to more difficult prose without using it as a crutch to obscure bad writing.