[this system we're considering] maintains the close connection between voters and their members of Parliament—one that Canadians are familiar with in single-member ridings

Lol. How many people can name their MP?

These arguments don’t hold up to scrutiny, though. In Ireland, PR-STV has worked well, and while it produces coalition governments, these have been stable administrations for decades that regularly run their full term. As for the argument that PR grants extremists and radicals a route into the legislature, to date in Ireland, the far right has failed to make electoral inroads despite the permissiveness of the electoral system. Instead, hyper-local independent candidates have become a staple of the political culture.

That feels like cherrypicking the one counterexample when there's a ton of straight examples of political fragmentation. Like, pretty much pick any different European country.