Eggs are consistent enough that they generally contain the same amounts of the relevant chemicals as another, similar sized egg. As a result, you don't generall

Eggs are consistent enough that they generally contain the same amounts of the relevant chemicals as another, similar sized egg. As a result, you don't generally need to weigh or measure the volume of your egg to achieve consistency, so long as your eggs are consistent. But you do need to use approximately the proportionately correct amounts of the other chemicals in your recipe. And you're just making your life easier if you measure those quantities in terms of mass, because it has all sorts of benefits: 1) You don't need to worry about packing - the same mass of table salt and coarse salt, sifted flour and packed flour, confectioners' sugar and granulated sugar; all will have the same amount of the active substance (but the form factor may of course have other effects on your recipe) 2) you can use a fine grained scale like grams, without having to introduce cumulative error (imagine if you tried to measure out 7/8 cup of flour by measuring 42 teaspoons - your error would be huge) 3) you can add it up across combinations of ingredients (100g of flour + 100g of milk weighs 200g; 1 cup of flour + 1 cup of milk has... who knows how much volume? That was, after all, the point of the original article at the top of this thread). This has huge benefits when adding mixed dry ingredients like mixtures of types of flour and cocoa, or mixed dried fruits, where you need to have a reasonably fixed total mass, but the ratios aren't as important. Just keep adding until you have the right total mass - something you can't do with volume. Measuring volumes is harder, less effective, and more error prone. That would all be the case even if you used a sensible volume measure like milliliters, but it's even worse if you insist on using a volume measure system made of arbitrarily named units like tablespoons and cups where you have to memorize a dozen conversion factors and work in fractions the whole time.