The issue is that every driver implementation ever ships with a slightly different implementation of that complex parser. That means (every mobile device)X(every OS update) and (every PC ad-in card)X(every driver update) all have the potential to misinterpret/reject your shaders in slightly different ways.This doesn't have anything to do with shaders as strings. It's been true since the beginning of shader programming, whether bytecode shaders or otherwise.
