Same reason why woke NPCs have danger hair

They are not complete by themselves.

Loss of self, loss of individuation, loss of personal goals, aims, needs and ambitions.

Merge into mass, merge into unity, outsource decisions, be/act like everybody else.

Classic brainwashing / conformism technique.

Why do cultists wear funny hats and costumes?

I would think it's numerous factors. Symbolism/color schemes, something about the materials it's made of in some cases, or maybe they're actually rather low-brow (or simply LARPing as such) and think it looks cool (How else would they recruit low-brow retards?).

a) suggested uniformity (sameness) tempts "one" to ignore perceivable UNI (Latin unus; one) FORM (differentiated through flow).

Same flow (inception towards death) generates different form (life)...suggesting form to behave the same tempts each one to ignore perceivable differences, hence ignoring to sustain difference (living) within sameness (process of dying).

Cultivating death by suggesting life to mimic its behavior...how?...by suggesting progressivism aka going with the flow, following orders, attaching oneself to the chain of command, being lead by others, hope towards outcomes; adhering to the main-stream etc.

b) consenting to suggested gives those suggesting the power to conceal it. Meanwhile...nature reveals everything (perceivable) to everyone (perceiving).

c) if the many consent to the suggestions of the few, then the selected few (elite) will stand out as the "chosen ones" from all the other ones, which the few conceal by setting substitute authority in-between themselves and their followers, hence those who suggest "in the name of" the few.

Among the many who ignore to see perceivable, those suggesting in the name of others have to be "seen", hence standing out differently among all those who behave the same. Meanwhile...anyone among the many standing out will be easily seen by the few (tallest nail gets the hammer) and resented by the many who just want to follow suggested orders and behave like the "norm".

Who are the mean looking cult of grandmas?