I player through the entirety of Final Fantasy VIII without draining magic or upgrading my weapons. I just GFed everything to death and healed as needed. Once you get to disk 4 however, this strategy no longer works and limit breaks and junctioning magic is key. Unfortunately without ever upgrading my weapons, I had nothing but the first limit breaks and weak attack power. You also get locked out of towns on disk 4, so there was no way for me to upgrade my gear. My save file essentially became unplayable and never really finished the end of the game.
I was young and new to JRPGs...don't judge me!