Because the errata are ever-changing, and some subjects will be errata'd multiple times. If there's more than one 'base' version of the rulebook out there, then they have to maintain a separate errata file for each edition for clarity, and that's only likely to cause more confusion. Keeping a single master text upon which to apply all errata does make a fair degree of sense.Whizbang Dustyboots said:That just seems odd to me. Surely they go to print more than once every three or four years. Why not update the plates, since most of the errata changes will only affect a modest number of pages?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.