Specialty Grain Steeping Volume

Hey guys, quick question. Most clones and kits I have done their recipe calls for grains to be steeped in a specific amount of water - “Steep Grains in 2gal of water at 170defF.” Prior to bring full volume to boil. I have also heard people claim to boil 1/2galwater to 1lb of grain. Why do they suggest steeping in a smaller volume than the full boil? What’s the issue with just steeping your grains in 6 gallons of water prior to boil, after time allotted crank it up to a full boil?

There may be less chance of tannin extraction in the smaller volume of water. The grains will act as a buffer if the water alkalinity is very high. Tannin extraction is a combination of pH and temperature. A pH of about 6.4 and above, with water temperature near or over 170°, can extract tannins from the grain husks.