It was never designed to allow a political body to force a President from office for a very personal mistake. Grand juries are not designed to search for truth. They do not and are not intended to ensure credibility, reliability, or simple fairness. They only exist to accuse. The law defines perjury very clearly.
Perjury requires proof that an individual knowingly made a false statement while under oath.
Answers to questions that are literally true are not perjury. Answers to fundamentally ambiguous questions also can never be perjury. And nobody can be convicted of perjury based on only one other person's testimony. The President did not commit perjury. Most of the illegal leaks suggesting his testimony was perjurious falsely describe his testimony.