Well, the problem is that, right? Product owner does not know about software architecture, neither code design. Often, when programmers talk about how to improve code infrastructure, the PO thinks that developers are overdoing, which might be perceived as a productivity risk. And of course, it might be not a crazy idea to think that if you spend the innovation day/week fixing things, doing maintenance, your developers may become upset.

That is a hard problem because in all the project, the only one that deals with the software, and understands it, is the developer. No one else can even grasp the complexity inside the code.