I'd just point out that this five drinks in three hours is one drink more than the rule of thumb often given out of two drinks in the first hour then one drink per hour afterwards. It's the rare 200 lb person that has 5 beers during a football/baseball/soccer game and is "very definitely impaired." Sobriety limits are justifiably geared towards the lower end to accommodate light-weight drinkers. This is even pointed out on the chart by noting that this is a 95th percentile drunkenness/BAC (i.e., 95% of people are LESS drunk/have a lower BAC than shown or, alternatively, 5% of people are MORE drunk than shown).
