Canada

Canadian governments have been able to pass significant legislation since repatriation. We're fine.

Centralizing power with the PMO just means the prime minister can make more partisan changes by fiat. We usually go to the polls every four years, so that's a long time to wait for accountability.

And of course, there's the problem that the PMO is responsible for so many appointments that they don't appoint judges in a timely manner:

"It is imperative for the Prime Minister's Office to give this issue the importance it deserves and for appointments to be made in a timely manner …The government's inertia regarding vacancies and the absence of satisfactory explanations for these delays are disconcerting."

...

"In some cases it may be that all relevant vacancies must be filled, as where serious crimes are not prosecuted in a timely way such that victims, the public and accused are denied justice," Brown said.