Is it thinly veiled homophobia?

Can anybody explain to me why so many parents have such a stick up their ass over their kids climbing up the slide? Go to a park sometime. I guarantee within five minutes you'll hear, "No no, honey, slides aren't for climbing... No, no, honey, we only go down the slide." or some variation therein.

Seriously my-generation, did you read some study that I somehow missed? Why are you so afraid of your kid going (gasp) the wrong direction on a slide? I understand if there's actually another kid at the top waiting to slide down. But barring that, they ain't gonna pop the tires.