Strictly speaking, 'social Darwinism' would be: describing
society, or aspects of society such as the
economy, in
Darwinist terms.
If done properly, this can be interesting.
To what extent does society behave like a naturally evolving system?
Do some of the same laws apply?
If they do, knowing exactly how is useful and important knowledge.
However, the idea is often mistaken for a moral judgement:
'the strong must survive'. Which isn't even necessarily true in Darwinism.