> Letters kept have always been accessible.
The physical letters, yes—but if those letters were written in a code or private language it is well established in precedent that one cannot be compelled to translate them into plain language for the prosecution. Forget all the false skeuomorphic analogies about "locks" and "keys"; encryption is not a safe you put your message into, it's a set of private codes.
A warrant authorizes law enforcement to seize the physical evidence (letters, hard drives, memory chips, etc.). Making sense of the content afterward is entirely their problem, and that remains true even when making sense of the content is likely to be beyond their capabilities.
The particular mechanism being exploited in this law (revoking section 230 protections for companies that do not implement whatever "best practices" are promulgated by this new committee) is particularly bad because section 230 should never have been required in the first place. It should go without saying that a service provider is in no way liable for illegal content uploaded by users without the service provider's knowledge. Putting aside the fact that the idea of "illegal content" is itself nonsense in any country that purports to recognize freedom of speech, the occasional removal of unwanted content that is specifically brought to a moderator's attention does not imply that the service provider actively controls everything that is published on the platform. Logically, if a fully unmoderated site is not to be held liable for content uploaded by users then a partially moderated one likewise should not be held liable for content which has simply not yet been brought to the moderator's attention. The court erred in lumping partially moderated sites in with ones requiring full prior review and approval before posting. Section 230 was passed to address this miscarriage of justice, and as such revoking or weakening its protections, or holding them hostage as this EARN IT act would, is itself unjust.