Diluting the value of items because the same effects are spread over more items in more slots could be a good thing: item quality can have low variance and power level increases can be much more gradual than with few, possibly overpowered items.
For example, suppose the character party is stuck at a certain combat encounter that regularly ends in retreat because the enemies can kill our heroes faster than the party can kill the enemies.
They have low attack bonus, i.e. they collectively lack items that provide good attack bonuses, relative to their progress in the game; let's assume the traditional D&D scale in which +1 to hit means hitting x+1 times rather x times out of 20.
At this point if they find their first enchanted sword and it is +4 (at least 25% more hits; the sword would be very valuable and possibly famous) the fighter equipped by it would be overpowered and the encounter would become easy, while if they find a +1 or +2 sword it would become winnable but remain challenging. And later they could find enchanted rings, bracers, underwear, etc. with small bonuses (usually +1, with +2 progressively less rare to provide an upgrade after saturating all slots with +1 items).