Please consider an ancient Green dragon with the variant ability to cast spells. She would like to cast Simulacrum.
Monster Manual Page 86 / Variant:
VARIANT: DRAGONS AS INNATE SPELLCASTERS: Dragons are innately magical creatures that can master a few spells as they age, using this variant.
A young or older dragon can innately cast a number of spells equal to its Charisma modifier. Each spell can be cast once per day, requiring no material components, and the spell's level can be no higher than one-third the dragon's challenge rating (rounded down) . The dragon's bonus to hit with spell attacks is equal to its proficiency bonus+ its Charisma bonus. The dragon's spell save DC equals 8 +its proficiency bonus + its Charisma modifier.
As noted she is CR: 22 with 19 charisma - giving her four spells to cast once per day / 7th level spell maximum. No problems thus far. She is concerned about the material components for this Simulacrum spell...
Components: V, S, M - Snow or ice in quantities sufficient to made a life-size copy of the duplicated creature; some hair, fingernail clippings, or other piece of that creature’s body placed inside the snow or ice; and powdered ruby worth 1,500 gp, sprinkled over the duplicate and consumed by the spell.
... but she realizes (thanks to 'variant', above) that she casts all her spells 'requiring no material components'. This is her lucky eon! She will have to choose fun spells like Awaken and Reincarnate so as to build up an immortal army of her favourite treasure-people-beasts! But she digresses.
This zero materials required means she need not worry over the expensive powdered ruby - nor even the snow for that matter. But what of the hair, clippings (or 'other body parts')? If ANY components are allowed, can she cast any humanoid or beast that has ever lived in history? She could theoretically magic-pretend that she procured these left over parts before that person or beast died. Can she even create duplicates of imaginary people with this casting? Is there a way that anyone could defend themselves from being copied? Some may have Mind Blank or Protection vs. Nasty &/or Goodness or reside on another plane of existence. How does one defend themselves from this 3D printer of doppelgängers?
The reason this is relevant: If she has access to any body parts without impunity, she could conjure up any high cleric or archmage in existence at no cost. The next day she could conjure up another, for free. This is bizarrely powerful. To be honest, even the ability to conjure up the same archmage from a specific ball of hair, gaining Wish on a daily basis (without limits) is a bit extreme.
Long story short: A dragon casts spells without need of ANY components. What kinds of Simulacrum persons &/or creatures can they make?