This is a popular history cliche that isn't grounded in actual history. See, e.g., https://acoup.blog/2020/01/17/collections-the-fremen-mirage-... for an accessible critique by a professional historian.

I do agree with your broader point though that it's worth asking if society is getting more illiberal and intolerant of opposing views. It's not just a "young people these days" kind of thing.