Why are has_one through has_one relationships not constructible in the same way that has_many throug

Per my question on StackOverflow: https://stackoverflow.com/questions/53243674/build-methods-for-has-one-though-has-one

And the subsequent answer there, I’m wondering why has_one relationships don’t behave the same way as has_many relationships in terms of building nested associations.

I assume there is good reason for this, however, I personally feel like this is a bug