The one with there just being dirt, and one that says the wall was just to leave a message, combine to make what is PROBABLY the most sensible answer (with the note that Ellen would not blatantly tell them the wall was just to leave a message, as that would be like having word of god on the matter).

Poor Ellen, however, PROBABLY doesn't want to end her game on "you accomplish nothing, your behavior was foolish, and you should be ashamed of yourselves."

I mean, sure, if people start swinging pickaxes at a wall in a fantasy world with text from another reality on it, they deserve to be called out on it, but that doesn't make that a good note to end on.