Draconic Sovereign Archetypes Question

[Getsugaru]

Specifically, where does it say that only True Dragons can take them? From how I've looked at it, I don't see why people say it's only for True Dragons. Can someone please help me?

EDIT: Also, a question about the Xorvintaal Dragon Template:

Spells: Xorvintaal dragons lose the ability to cast spells.Does this mean that a dragon with this template loses innate spellcasting, or if they, for example, had taken levels of cleric, would they lose that casting too?

[ThiagoMartell]

Specifically, where does it say that only True Dragons can take them? From how I've looked at it, I don't see why people say it's only for True Dragons.

It's context. Dragons of Eberron is about true dragons. The prophecy is about the dragons. The text in sovereign archetypes only mentions true dragons. There is a blurb at the beginning of the book saying "guys, it's all about true dragons".

[Answerer]

EDIT: Also, a question about the Xorvintaal Dragon Template:
Does this mean that a dragon with this template loses innate spellcasting, or if they, for example, had taken levels of cleric, would they lose that casting too?
RAW, it's all spells. Seems to me that it would not be unreasonable to have it apply only to their innate spellcasting, but that is not how the rules actually read.