Why aren't side-content points of interest farmable? This is a loot-based game

You added all these side content things for players to seek out if they feel weak/behind the content.

So why can we only get them once? If we still feel weak and feel we need more, why can't we spend the time and effort farming them?

Would it really break the game? Why can't we grind items in an item grinding genre?

Where's the RPG in ARPG? Starting to think this is more of an A game. Action game. With a seasoning of RPG elements.