Why Sated Devourer's Phantom Hits Violate Riot's Expressed Ideas About "Balance Levers"

I recall Riot's design team often talking about "balance levers" when discussion their champion designs. The basic idea from what I understand is that it's beneficial to design a champion with as many directly nerfable/buffable aspects (scaling/bases/ratios/ranges/cooldowns/durations/percentages/etc.) as possible as this makes the champion far easier to balance when the need arises.

The core problem with Sated Devourer is not the stacking system, nor is it the on-hit magic damage. It's the fact that phantom hits cannot be nerfed. Phantom hits simply do or don't. The only way to technically nerf something having too much synergy with phantom hits is to nerf that something, making not just Devourer itself weaker, but also making the target of the nerf weaker without Devourer, as well. Making the item slower to stack simply delays the problem instead of fixing it. Toxic gameplay is still toxic gameplay be it at 20 minutes or 50.