It's because of the time. The owner wanted to imply cleanliness in production, chemistry was pretty new, and what could be cleaner than water? Hence Hydrox

"A lot of people worked really hard on this."

"Why?"

Last time I tried Hydrox, arguably many years ago, it seemed to taste and feel like all the generic knockoffs. They would start off crunchy when you first open the pack but would turn soft and stale within a couple days. Oreos seem to stay crispy for literally weeks.

From personal experience, Hydrox tasted terrible compared to Oreos. My parents switched to Hydrox when I was little because Oreos were being made with lard at the time, and they were barely worth eating. The chocolate cookie part was too hard and chalky.