Your approach can certainly work if a policy has enough approval from the electorate, or if most people don't care about it, but not here.  The issue is fundamental, people do care, and the fact is that, if a referendum were held, first-past-the-post would beat the alternatives. A government that tried to force an alternative through without a referendum  would be defeated at the first opportunity, simply on the charge of extreme arrogance. The next government would then repeal the change. Arrogance being the particular Achilles heel of the Liberals, Trudeau did the only thing he could have done. He will pay a price, but nowhere near the price he would have paid for forcing a new electoral system on the public.