Batch size and measurement precision
Commercial brewers creating barrels or hundreds of barrels of beer in each batch, can get by with coarse measurements of malt, water, hops, acids, and minerals. But homebrewers with their smaller batch sizes, need to pay more attention to measuring those items. This is particularly true as the batch size gets really small.
The growing popularity of brewing very small batches in the 1 to 2 gallon (4 to 8 liter) range, makes it more critical to make sure your measurements are more precise. That means that measuring those items down to the milliliter or milligram needs to be a consideration. using measures like fractions of teaspoons, ounces, pounds, or kilograms might be too imprecise for getting elements like your water/grist ratio, mineral content, bittering, and mashing pH correct.
That may mean that its time to get a precision scale and graduated cylinder for brewing those small batches. While those tools are still important to commercial and home brewers, they are critical for small batch brewers.
Enjoy!