[dlss]

This is a deep question. Brainstorming I get:

- Steve and Alex founded reddit fresh out of school, and schools don't generally teach databases beyond the theory

- Fresh out of school, they didn't have the opportunity to learn it from someone with more experience

- They were busy building the rest of the site, and so didn't spend the time to delve in to these concepts

- Paul either didn't feel the need to explain it to them, or had reasons similar to the above to not know

Hmm... I'm out of ideas. Anyone else?