The ops teams I've worked with watched graphs because (a) sometimes you see interesting changes or trends before they turn into actionable alerts and people can look into them/figure them out before shit's on fire, and (b) it makes it look more like you're doing something when everything is smooth sailing and not actively on fire, solving the "wait why are we paying for this if it doesn't take us long to respond to incidents anyway" naive-meddlesome-exec problem.