Aye - but at least it informs people of what they're not SUPPOSED to do - if they see some pile of old candles and stuff on a monument, they'll not see anything wrong with it and possibly add more cack. But if they KNOW it's wrong, they're more likely to think "tsk!" and not add their own cack, or even clear the existing cack. Possibly.
Well, it's not a bad thing to educate people in these things, regardless, is it?