There's a universal subconscious assumption that "They" are

Assume implies "to take upon ONEself"...assumption implies a singular undertaking. It's the suggestion of ones singular assumption which establishes a plurality.

The origin of plural implies singular taking for self, while withholding from one another.

everything "They" do is inimical towards the rest

Everything implies each thing within...it's the singular thing summarizing things together which establishes animosity.

There's nothing inherently bad

Bad implies versus good...versus/verto - "to turn" implies friction among many by turning against one another, which continuously worsens both sides. It's the versus in-between the sides (good or bad) which represents adherence/haerere - "to stick together".

I mean, within reason.

Good versus bad implies reasoning...