This helped my nostalgic craving for those pedantic old school HN comments which I seem to see less of nowadays...But frankly as a kid playing in the pool often revolved around pretending to be some kind of sea creature.

The obvious answer is because the old, crudely drawn sign did (and to go deeper, you'd have to ask the janitor who drew it.) Now it's become completely detached from its origin and pointless.

The only reason this question is answerable is because the poster saw the old sign. When everybody is gone who saw the old sign, they'll just continue doing it for no reason. When somebody asks about it, some creep will babble about Chesterton's Fence.

As someone who laps in a pool with fish in it occasionally. It could be true. (google Sydney ocean pools to see what I'm talking about)

Preschools decorate lists with little pictures on the sides. In most preschools that I’m aware of the person who makes that list makes minimum wage and has 4-8 children to keep alive while she’s making that list.

This is such a weird thing to get worked up over.