@IndyRichard@mastodon.scot
That depends on how essential to fascism you see the racism and scapegoating aspects of regimes like the Nazis. I think they are, to be sure, always present - but then they are endemic in all right-wing politics, and if like Eco we define fascism with a very extensive list of characteristics, we find it becomes ever-harder to distinguish from many other regimes we don't generally designate 'fascist' - there have for example been many authoritarian absolute monarchs in history that were racist, etc - but nobody calls them fascist.
I think fascism is rather a very specific evolution of capitalism - it is 'the continuation of capitalism by undemocratic means' - a reaction of the wealthy and privileged to the imminent loss of their status (or perceived danger of that loss). That's what happened in Europe in the 1930s, and Chile in the 1970s - and the US in the 2020s.
And there's an often overlooked aspect of Nazi antisemitism: it conflated jewish and communist conspiracy. The first concentration camps were in fact not for jews at all, but for communists. If you look at the pro-Nazi jewish magazine Der nationaldeutsche Jude, anti-communism, and the post-Russian-Revolution association of slavic jews with communism, is a central theme.
Nor were other fascists like Franco and Mussolini more antisemitic than most of their contemporaries, but they both explicitly conflated the ideas of communist and jewish conspiracy - and contemporary fascist thinking elsewhere during the Great Depression - Oswald Mosley, for example - was very centred not on racial, but on economic issues, and predicated on the idea that communist revolution was imminent.
Mosley's grandson, Louis Mosley, by the way, is CEO of the UK division of Palantir - https://www.thenational.scot/news/25759699.palantir-uk-boss-louis-mosley/