Here's why:
* Valid is an adjective, meaning "being sound, just, or well-founded."
* The past participle is used to form perfect tenses (present perfect, past perfect, future perfect) and passive voice constructions.
* Validated means "to make or declare valid."
Examples:
* Present perfect: The document has been validated by the authorities.
* Passive voice: The new system will be validated before it is released.