It's completely untrue. It's unfortunate the Toronto Star continues to mislead its readers on this question because voters don't have access to an adequate education campaign.
Most jurisdictions which use MMP have a history of very stable, effective governments that last for many years between elections. Comparing the results for the German and Irish proportional voting systems with results in Canada we see that the frequency of elections is unlikely to change significantly :
Ireland: 16 elections since 1948 - 1 election every 3.63 years
Germany: 16 elections since 1949 - 1 election every 3.56 years
Canada: 18 elections since 1945 - 1 election every 3.39 years
In these two countries, majority coalition governments are the norm. The great majority of major democracies are governed by coalitions. In fact, many countries (including Switzerland, Germany, Belgium and the Netherlands) with very diverse populations have a history of very stable coalition government.
It seems the Toronto Star's research on other systems around the world stopped at Italy and Israel, both of which only suffered from instable governments when they had all-list Proportional Representation. To compare Ontario's version of MMP to those different versions of PR is disingenuous, but what else would you expect from the Star in this debate?
There are many people who wrongfully believe that minority governments or coalition governments can't get things done. Nothing could be further from the truth. Minority governments have a great history of accomplishment in Ontario, across Canada and around the world.
Mike Pearson's Liberal minority government in the 1960s not only introduced Medicare in Canada, but also many historic changes including the adoption of our Canadian flag. David Peterson's Liberal minority government from 1985 to 1987 was viewed by many to be one of the most effective and accomplished governments in Ontario history.