A 80Bronze 300W can still be more efficient than a 750W 80Platinum on mainly low loads. Additionally, some of the devices are way more efficient than they are certified for. A well known example is the Corsair RM550x (2021).
If your peak power draw is <200W, I would recommend an efficient <450W power supply.
Another aspect: Buying a 120 bucks power supply that is 1.2% more efficient than a 60 bucks one is just a waste of money.
Modern Power MOSFETs are cheaper and more efficient. 10 Years ago 80Gold efficiency was a bit expensive and 80Bronze was common.
Today, 80Gold is cheap and common and only 80Platinum reaches into the exotic level.