This is true in my opinion. The different guns in gears make you play differently, and the enemies force you to use your guns and your allies in different ways.Your comparison is wrong tho, you said that picking up another gun completely changes the gameplay dynamic of gears and that last of us doesn't have that.
Check dishonored for the true meaning of this statement.You can literally approach any situation in a dozen different ways and the gameplay will change accordingly in last of us.