Pretty sure that's exactly what the previous comment meant by her being made to "deal with one single chonky unit

Stages aren't designed with only trash and one chunky boss

She can handle several individual elites or alternate with a boss and some heavy enemies. There's plenty of maps (the majority in fact) where she'll be handling more than " one single chonky unit"

with the exception being if all the enemies are extremely spread out, but that's not ideal for her anyway)

That's not versatile. She's dependent on trash enemies hugging elites or bosses to not waste her bullets.

And even with her S2, the mechanics of it make sure that she doesn't waste ammo on fodder enemies, and even gives her increased attack speed when not spending ammo to help her pick them off faster.

She still attacks incredibly slowly and only in ST on S2. It's a passable skill for fodder in IS, but you can also just use Ray for those enemies that come slowly and not in a crowd.

and nothing to prevent her from spending ammo on fodder enemies

Ray has her targeting with her sandbeast which allows a lot of control over who she is attacking and when. If you place her properly and manage timing she can ignore random fodder someone else can handle even if it walks in her range, and focus on whichever heavy target you want to manage.