This statement is also wrong. I farm at Master's league and I care about trophies all the time. Getting 50% keeps me from dropping to Crystal I and I get some good loot bonus. Also, people farm at certain trophy ranges to get certain loot, so trophies are important and can't be ignored while farming.
EDIT: May have misread that last part. If you meant the game's goal as in getting as high in trophies as you can, then your statement is true. Not sure what you mean so I apologize in advance if I made a mistake.

