Because humans are really good at seing patterns. I've been saying this for years now in the context of sysadmin work and dashboards. Some people think about

Because humans are really good at seing patterns. I've been saying this for years now in the context of sysadmin work and dashboards. Some people think about graphs in dashboards as pointless frivolity and for show. I've heard/seen people claim: all we need is an indicator: green if OK, else red. In my opinion, while that is useful, in my position that is often too late. Always visible that shows whatever is important to my work: disk space, numbers of errors, (mega/giga/tera)bytes in/out pr second/minute/hour, that allows me both to predict and react, often ahead of time and also to easier diagnose, both because I now have an eye into the system but also because I have over time built a feeling for what is normal and not. The same is true for visualizations and we also have the same enemies, for example misleading scaling and too little/much detail, distracting details and colors that looks way too similar.