@flo As I said earlier, “low ability” could be referring to a specific area of knowledge that they are lacking in, whereas when someone is called “stupid” it’s generally understood to mean that they’re just not smart about anything. Given that, I would say there is a meaningful distinction between the terms.
Vaccination is a great example. I would say that I have “low ability” when it comes to immunology. It’s a massive field of study that’s constantly evolving. I have a crude understanding of how vaccines work, and a basic understanding of herd immunity. I probably understand vaccines better than a large majority of Americans, and yet I’m still of “low ability.” I certainly don’t consider myself stupid.
I completely agree though that personal attacks are unhelpful and ineffective in making convincing arguments.