The question was raised more than once during committee discussions.
When we say "the necessary measures", their necessity must be proven. Often, a stakeholder must prove that a specific measure is necessary, or the minister must be persuaded of its necessity, which can add needlessly to the burden of proof. It could even dissuade certain ministers from implementing positive measures because they would not be deemed necessary.
It explains the wording still used by legislative drafters in Bill C‑13, which specifies that federal institutions must implement commitments by taking measures "they consider appropriate," or possible measures, rather than talking about measures deemed necessary, because that requirement adds to the burden of proof.