> The best explanation I heard for the appeal of fascism was from someone on the far-right – that fascism is basically an immune response of a nation.

This is some really low-tier fascist apologia, in my opinion. Fascism isn't an immune response, it's a cancer. Once active in the host, it tries to sap it of whatever resources it can to enrich itself. Rooting out fascism has, historically, come at great personal and political cost to the countries that manage it.