Overall a novel idea that I like. That said, the only reason this is an issue is because once you've seen a level being played (or in this case, you making the level), you know the solution.
There's a difference between difficult & completely obtuse level design. I'm more concerned about there being an incredible amount of levels made which are difficult not due to challenge, but due to people not knowing how to make challenging levels that don't require some incredibly obtuse solution that only the person who made it would bother to guess.
Hopefully there's a user rating system on-top of the difficulty system mentioned. I know user ratings aren't the most reliable indicators of quality, but If there isn't one, every time I pull up a "difficult" level to play, i'm going to wonder if i'm pulling up a legit difficult level, or a garbage level that only the creator would bother to figure out.