Last I heard this is WGT golf and NOT the f-ing PGA Tour. And even if it was the PGA Tour I can use ANY CLUB on the green...even the putter.
So, in terms of golf etiquette/rules, I have not violatied any rule if I choose to never use a putter on any green. Just think of the PGA Tour professional who first decided to put a 5 foot putter in his bag and levered it off of his chest. I’m sure he heard, “WTF are you doing” but he wasn’t breaking any rules. Then other professionals adopted that putter.
Overuse of a “valid” shot is not a violation. If it bothers you if your opponent plays this way then maybe you need some therapy or some anger management sessions.
For instance, I suck at the punch shot which is more accurate than the approach shot methods I use in this game. So am I supposed to quit if my opponent uses the punch shot over and over during our round of play and knocks them within 2 feet? No, I just have to realize they’re better than me in strategy and execution...plus, maybe I should take some time to practice the punch shot.
BOTTOM LINE: Use the tools you know, and learned how to use best, in order to finish the round in less strokes than your opponent.