While this is completely true, it misses a fundamental aspect of the game, that of compromise and bottlenecks. (not debating if that method is good or bad)That pretty much depends how much of a hurry you're in. Once you've acquired ENOUGH sectors to open the next Advance Scouting chest, it's sort of crazy to more on scouting than need be. At that point it makes total sense to do Tournaments while you're wait for the 25% cost reduction, and larger squad sizes, that will be available in the subsequent chapter.
By adding tournaments and using them as you quite reasonably suggest, you use significantly more supplies to make the troops. If you are speeding through as fast as you can, you will only have enough workshops to make enough armies to get through the scouting missions. To ALSO run tournaments, you need more workshops (and also more than you will need end game) and something else has to suffer. Perhaps the RP rewards are worth it, as this is the direct way to trade supplies for RP. Until some math is done, tournaments look like a drain with little gain, until you get near end game. Plus they don't work as designed for some people.
So to relate this to the topic, Tournaments do NOT make the MA worthwhile, as they both are not implemented properly and they take away your progress. Tournaments and MA both suffer from a lack of foresight and an unwillingness to fix them. Or being ok with putting out substandard fare.