An item cap is really needed, especially for games that use persistence, Creative isn’t the most stable so there’s been many glitches and opportunities for cheaters to bring in billions of different resources, these then save and are with the player forever, they can drop stacks of millions to hundreds of players, ruining a maps in-game economy.
This then leads to a whole load of other issues, a save data reset is the only way to fix, which affects all aspects of persistence as we can’t individually control what is reset, and that doesn’t tend to go down with players very well.