This is true to an extent (and in basically any pro tournament even the best players in the world can disagree about complex interactions and need a judge). But I've rarely found it matters with beginners - just start with vanilla creatures and simple removal if you're worried, my kids learned the structure of your turn, paying for spells and combat in about 10 minutes. Everything beyond a few keyword abilities is just reading the cards, you don't _really_ need to refer to the rules for the most part. This is in stark contrast to Yu-Gi-Oh, we've found, where you can't just play what's in front of you.