According to the article yes, the issue is "what is a class":
"You have to understand how this works in JavaScript, which is very different from how it works in most languages. You have to remember to bind the event handlers." etc.
Eh, even in the same paragraph it says "The distinction between function and class components in React and when to use each one leads to disagreements even between experienced React developers."
Also, bits of class issues show up in the other complaints.
So, no, it's not just "what is a class" and it's a weird hill to die on. I feel like most of these responses to hooks in general just focus on the most trivial detail aka bikeshedding.
I'm focusing on classes, because it seems to me that to "React" classes are a necessary evil (or they are treating them like they were).
Hooks, suspense, context wormholes - I'm not sure if these features should be part of a view engine. React, to me, did one thing and did it well, but now... I don't know.
Can't argue with the text of the article. I do, however, stand by why _I_ have found that classes are a bad match for this need, and watching the video of the demo did a much better job of suggesting the benefits and reasoning...reasons that don't really match the parts of the article you've quoted.
"You have to understand how this works in JavaScript, which is very different from how it works in most languages. You have to remember to bind the event handlers." etc.