The article says:
In countries such as Britain, France and Germany, where the center-left was in government in the early 2000s, it is regarded by many voters as having been a zealous accomplice in financial deregulation and economic liberalism.Translation: from the viewpoint of the radical socialists, the "center left"(Europe's moderate left) is being blamed as having sold out socialism. Just as we're pissed at RINOs, the European radical Left is pissed at their moderates, however Leftist their moderates may appear to us.
Most european left has moved to cut taxes for big business and privatizations. For example, the corporate tax in Germany has been slashed in half in last decade, when social democrats ruled the ministry of finance (1998-2009). The tax burden in Scandinavia is among the lowest too. They have massively replaced the class warfare principles for modern “progressive” issues: abortion, gays, feminism, multiculturalism... Pissing the most ideological left-wing electorate (the far left is growing too). At the same time they have lost many voters who are low-skilled native workers, frightened by massive immigration. In Denmark, the most voted party among low-skilled workers is the right-wing populist Dansk Folkeparti, not social democrats anymore.
Then you have only 5 left-wing governments in the European Union: Austria (grand coalition), Portugal, Spain, Slovenia and Greece.