The fundamental problem with…

The fundamental problem with MZOs not having to be consistent with the PPS is that those portions of that document which relate to Indigenous Treaty Rights flow directly from Section 35 of the Constitution Act. Accordingly, an MZO which proposes to ignore protections on the environment or on archaeological resources would be in contravention of both the Constitution and the Duty to Consult it creates - as established by the Supreme Court of Canada. I can understand the desire for haste when it comes to building new housing or the approval of resource projects, but it is simply inappropriate for local, provincially-regulated projects to be exempt from the principles laid down in the foundational document for the entire country. The Supreme Court has been clear that there must be no "sharp dealing" on the part of the Crown when it comes to the First Nations who, by virtue of being in a fiduciary relationship with the Crown, have been put at a disadvantage when it comes to protecting their own interests.
Most First Nations communities in Ontario have treaty rights that include the right to hunt, fish, and gather foods and medicines from their treaty lands - into perpetuity. Taking such lands out of circulation as part of a resource development or a housing project impacts those treaty rights - which is why the current PPS requires Indigenous engagement in an open and procedurally-fair process. If that process seems too onerous and the government excuses itself from that consultation via an MZO, it breaks promises which the highest court in the land has determined are unbreakable - and drives home the point made by some Indigenous community leaders that our legal system does not protect the interests of the First Nations."
As was made clear in the final report of the Truth and Reciliation Commission of Canada (TRC), whenever Canadian governments have used their authority to ignore or suspend the legal rights of the First Nations, it has both harmed their communities and been an embarrassing blight on our record. It's 2021. We should be past this sort of thing.