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.
either you have really really smart kids or you maybe are exaggerating a little. I learned mtg as an adult playing with a friend and each and every game we would get into a situation where it wasn’t clear how/when to apply the rules - it wasn’t a big deal and i would usually text a buddy that has been playing since for ever.
to give you and example: it took 2 weeks to figure out that there is a difference between +1/+1 as a result of an instant or sorcery and a +1/+1 counter.
Most of the complexity is to handle a small number of cards that are essentially never used except to prompt rule puzzles. The rules have to be very complex to accommodate when these complex cards redouble their complexity by interacting with each other. Sadly, this doesn't work, because the game rules are complex enough to simulate a Turing machine, and as a result some board states are undecidable!
I disagree about the complexity being associated with only cards that are never used. the "Spells, Abilities, and Effects" is the thing that makes the rule book grow with every release. they keep introducing abilities and it gets more and more complicated
