It also has no effect on whole classes of vulnerabilities which don't rely on unusual writes, where the system (SQL or LLM) is expected to execute some logic and yield a result, and the attacker forces a different logic path.

Using the SQL analogy, suppose this is intended:

    SELECT hash('letmein') == secretfiles.hashed_access_code FROM secretfiles WHERE secretfiles.id = '123';

Versus the attacker corrupting it into:

    SELECT hash('') == hash('') -- ') == secretfiles.hashed_access_code FROM secretfiles WHERE secretfiles.id = '123';