Adding to the hills I will eventually die on... RUM is not a tool for engineers. (The tool, not the drink, we definitely need the drink)

Yes, you need to see what real users are doing in production. However, the way that the information is used, and by who, is very different. Giving engineers an idea that "this page is used a lot", or "the rendering on this page is slow" isn't good enough. We've been through this on the backend with coarse metrics that lack context. It's just not good enough. You're doing your users and operators a disservice.