I did game development in a previous lifetime. Probably half my day was implementing algorithms and thinking about the correct data structure for a problem.

I spend less time these days implementing algorithms. However, you need a good understanding of algorithms to decide between using ActiveRecord or a service layer. You need a good understanding of algorithms to pick between a relational DB, a key-value store, or a document store.

Maybe you aren't picking difficult enough problems if you don't have to think about this kind of stuff.