My 2.5 year old is obsessed with climbing into the baby's things- especially the swing these days (figures- she hated the swing as a baby). The weight limit on all these things is usually 25 lbs or less, and she weighs almost 30 lbs. anything she would get hurt if it broke, I stop, or if it's super essential, like the rock and play.
Everything else I just cross my fingers that the weight limit is conservative. I cant fight every battle.