This is a change in degree, not kind; every developed economy is somewhat social democratic. Even the USA has minimum wage, social security, medicare, medicaid, food stamps etc. The debate is not whether these things are necessary, rather it is a question of how much to spend and how best to direct them.
The decades since 1980 have seen a broad swing to a neoliberal consensus in which these things are to be reduced in order to reduce government spending, which in turn allows for increased economic activity in making things, which is supposed to make everyone richer. However we are now seeing that the last bit doesn't work very well, leading to pressure to do something about it.
This political pressure currently shows up as support for populist candidates who promise to solve the problems caused by "them", for various values of "them" (e.g. the feckless poor, the liberal elite, the media, foreigners, Eurocrats, drug dealers, jews, blacks, whites, muslims, gays, the list is endless). However amongst all the competing targets the big persistent one is of huge multinational companies and their billionaire bosses who pay little or no tax quite legally while telling the rest of us to tighten our belts.
The big problem for such "tax and spend" policies is simply that taxing the very wealthy is currently not possible: if you put up your tax rates the profits and income you were going to tax somehow evaporate and emerge in another jurisdiction with lower tax rates.
Maybe I'm an optimist, but I see this leading to a new consensus in which tax havens everywhere (including the USA) come under increasing pressure to share information about beneficial ownership and money flows, allowing governments to effectively tax the very wealthy and spend the money on social safety nets, UBI and health care.
If 3D movies are ever to become important then directors are going to have to avoid close-ups.
"The voters have spoken, the bastards..." -- unknown