Minecraft wiki entry for Hunger_management, associated text: Advantages:
Cause temporary constant health regeneration that is not dependent on the player's hunger.
The rate of regeneration is faster than the natural health regeneration in Bedrock Edition and before Java Edition 1.9, making them useful in combat and emergency situations.
Compared with potions of regeneration, their effects are available without the need for brewing, which is only possible via accessing the Nether in singleplayer.
Not to mention that golden apples are stackable up to 64, but potions are not.
Tree farming can provide a good supply of apples. Trading with farmer villagers can also get them in quantity.
Can be used to cure zombie villagers. If generated structures are turned off, this is the only way to obtain villagers and trade with them.
Although they restore fewer hunger points, they grant 5 seconds of regeneration II and 2 minutes of absorption, giving the player an extra 4.
Restore 9.6 saturation, a large amount considering their low hunger restoration.
They can be eaten while the hunger bar is full, which means the player can maintain a high level of saturation (and the natural regeneration it offers) without being only able to eat until the hunger bar starts draining.