Thatcher is the 'reality of capitalism' at a certain cycle. It was scarcely unprecedented to have 3 million unemployed. It happened in the 30s, without Thatcher, to give but one example. The only difference was she actively promoted unemployment as a way of cutting wage inflation and breaking the power of unions. It worked - from her POV and that of the many who thought like her.
What we had between 1945 and 1979 was capitalism managed to minimise unemployment. That was why, for example, huge factories created to build and maintain steam locos were continued, year after year, until they became completely untenable. Because many employed 2000-3000 skilled and semi-skilled men whose training fitted them for very little else in a changed world. No one - not even the Tories of the time - relished putting these guys on the dole. In fact, for many years they shrank from it.
It was a priority by political consensus, after 1945, to maintain full employment. People were scarred by the 1930s and it believed - rightly, I think - that mass unemployment had contributed to the rise of fascism. (It certainly had in Germany.)
For a time this was not hard to achieve. There was plenty of work reconstructing the UK, and there was a natural shortage of men caused by death and disablement in WW2. This led to both immigration and a growing role for women. Inflation arising from the choice occasionally caused concern, but no one wanted to tackle it. Until, as inflation does, it began to run out of control in the 1970s.
Thatcher believed this consensus led to inefficiency, overmanning, excessive power for unions and high inflation. It's hard to deny she was at least partly right, but her 'solution' was brutal and broke the social cohesion of the UK. Arguably forever. We have never been quite the same country again, because we went down the path of kowtowing to individual greed and selfishness.