I'm going to go a bit further than just not understanding, I'm actively disagreeing with you. Based on your arguments here, in a workplace I would advocate not letting you make any decisions about database schema.
Sounds like the feeling might be mutual there though. Not saying you're bad at whatever it is you do; just I want to have to have schema designed by someone who has thought deeply about schema design. Databases usually outlive all the employees assembling it, can outlive an entire organisation and getting the design right can save days to months of work.
The academics have got entire classes of bugs that they can demonstrate don't exist in normalised data, there are benefits to everyone coordinating around a standard shared view on how to lay out data and usually drifting away from the standard it turns out not to lead to real benefits long term. You can believe that is valueless or isn't math or whatever, but there is no point aggressively introducing opportunities for bugs when there is no reason for it. And to avoid doing that, the person making the decisions needs to understand the theory.