They also were both high status individuals who lived almost exclusively in the world of academic disagreement. It's not that difficult to be open-minded when closed-mindedness has little physical consequences for you.
If you live in a town in Myanmar where some heated discussion on the internet can turn into an ethnic riot and end with you dead on the street, or you're a Chinese shop owner and some garbage on the internet ends with your store being destroyed you get a little bit more careful about the "sticks and stones may break my bones but words will never hurt me" attitude.
The shifting attitude towards offense isn't so much the result of technology as the article suggests, or changing culture in the upper strata of society, it's democratisation of discourse to people for whom discourse actually matters in the real world. I think this is why the change has been so pronounced in the US in particular. In the US, average people for the longest amount of time had no ability to speak at all, all discourse was 'free' because it was free from consequence for the people who spoke, in practical terms.