but spelling and grammar still isn't a good indicator for expertise, intelligence or anything like that even in an academic context
Mainly:
1. Dyslexia doesn't make you dump, just likely to misspell and a less likely to notice your misspelling.
2. When speaking about neurodivergence people mainly think about Autism or ADHD but sometimes just mean that your brain thinks in very different patters, this can make grammar hard. Especially if it's not your native language.
3. Sometimes people had shitty situations earlier in their live, leading to incorrectly learning parts of languages. This is hard to fix. But isn't really representative in any way for their expertise in any topic which isn't the given languages grammar.
4. English grammar and pronunciation to spelling mapping aren't exactly well designed. People not wanting to bother with it is not really related to intelligence, or excellence in other topics.
5. Some kinds of expertise are unrelated to general intelligence, expertise, education. So even if spelling and grammar where related to intelligence, it wouldn't be meaningful to judge expertise.
I think the grammar/spelling is just one (perhaps low-signal) sign. But a lot of these people really are not that intelligent. And not just the GlobalElite™. Think of the guy who owns the local car dealership or owns 20 laundromats in the surrounding 3 counties. These guys are not geniuses, either. They just happen to own things that make them rich.
I worked with a tech founder at one point in my life, and I once happened to get a glance at his undergrad college transcripts which were, for reasons unknown, just sitting out on his desk. It was all Ds and Cs. He barely graduated! Yet his networth was more than the combined net worth of all of his employees.
Your GPA isn't necessarily a measure of your intelligence. I graduated with a 2.01 GPA from college, because I spent most of my time learning about technology and things that interested me, and doing the bare minimum to pass my classes.
But my diploma still says "UC Berkeley" on it, just like the guys with the 3.9 GPA. And when I hang out with PhD friends' PhD friends, they just assume I'm a PhD too.
So what I'm saying is that sometimes smart people don't put a lot of effort into school.
I can't tell my kid with a straight face, "Work hard, study, get good grades in school, and focus on a good career" when I know it's fucking bullshit. And what I should be saying is "Sorry that I'm not rich and well connected--since that would have been the outsized predictor of your life success."
It is just also not an argument against their intellect either.
Just look at what they nonsense they say all the time, and how they arguments and reasoning is commonly full of hols and messy entangled problems often stump them.
Similar for many cases where it's publicly visible its very clear that their success story commonly highly relies on stuff like knowing the right people and luck of having the right think at the right time with the right supporter.
But it would be a mistake to assume that non of them are very intelligent (or that non are quite dump), that would run at risk of underestimating how dangerous they can be. Both in "clever dangerous" and "idiotic dangerous" ways.
The reason I care about this is because if you ignore the US for a moment in a lot of places the same kind of "all connections often little substance" elite exist, just with having bothered to learn to use "extra" eloquent language to the as arrogant if not even more arrogant look down on people.
Which brings us to another reason why it isn't a good indicator: In the same way that "elites" use eloquent language to differentiate them self form common people do the "elites" around the trump camp differentiate them-self by explicitly not using it.
but spelling and grammar still isn't a good indicator for expertise, intelligence or anything like that even in an academic context
Mainly:
1. Dyslexia doesn't make you dump, just likely to misspell and a less likely to notice your misspelling.
2. When speaking about neurodivergence people mainly think about Autism or ADHD but sometimes just mean that your brain thinks in very different patters, this can make grammar hard. Especially if it's not your native language.
3. Sometimes people had shitty situations earlier in their live, leading to incorrectly learning parts of languages. This is hard to fix. But isn't really representative in any way for their expertise in any topic which isn't the given languages grammar.
4. English grammar and pronunciation to spelling mapping aren't exactly well designed. People not wanting to bother with it is not really related to intelligence, or excellence in other topics.
5. Some kinds of expertise are unrelated to general intelligence, expertise, education. So even if spelling and grammar where related to intelligence, it wouldn't be meaningful to judge expertise.