I think people get confused. They see people they think are hard-assed, no nonsense types, but don't exactly get what's happening. They conflate how they felt with what was said.
For instance, Bob is just starting out as a junior dev. He gets pulled in by Carl. Carl is project lead and everyone admires him. Carl is smart, quick, and insightful. He's seen as a bit of a hard-ass, but he's never wrong. He cuts through bullshit. So he pulls Bob in. And he tells Bob, "I've reviewed your last commit, and here are problems X, Y, and Z with it. X causes this. Y is deprecated and B is how we should be handling the issue now. Z gives the wrong result for this set of cases."
And Bob leaves and Bob feels bad. He feels just reamed. Seemed like nothing he did was right. So he gets this impression in his head that Carl really laid into him. Fast forward 10 years and Bob is now a project lead and he wants to emulate Carl. Because despite how hard Carl was, Bob learned a lot. He's a lot better than he was back then. Now, he doesn't think he'll ever be Carl, but he's still good.
And Bob is reviewing Dave's code, and Dave's code is just as bad as Bob's was 10 years ago. So Bob calls in Dave. And he lays into Dave, "Just what the fuck do they teach in school now? Look at what you did here. You fucked it up. Don't you know about A? Or B? You have to do better."
And Bob feels good, he gave a "Carl"-style rant and now Dave will get better.
But reread how each approached their junior. Carl didn't attack Bob at all. He focused on the code itself. Bob internalized the criticisms of the code and took it personally. So when it was Bob's turn to criticize, he made it personal. Of all the lessons he was given that day, he missed the most important one.
So, you see "This commit is bad because of [X]" as polite, because you aren't the type to internalize criticism of work as criticism of you. People who do internalize it, see it as one and the same and feel that comment as "brilliant asshole".
The kind of brilliant asshole you describe, aka Bob, hangs on a bit longer because he's not bad at his core job, it's just that he has a tendency to handle people poorly.
For instance, Bob is just starting out as a junior dev. He gets pulled in by Carl. Carl is project lead and everyone admires him. Carl is smart, quick, and insightful. He's seen as a bit of a hard-ass, but he's never wrong. He cuts through bullshit. So he pulls Bob in. And he tells Bob, "I've reviewed your last commit, and here are problems X, Y, and Z with it. X causes this. Y is deprecated and B is how we should be handling the issue now. Z gives the wrong result for this set of cases."
And Bob leaves and Bob feels bad. He feels just reamed. Seemed like nothing he did was right. So he gets this impression in his head that Carl really laid into him. Fast forward 10 years and Bob is now a project lead and he wants to emulate Carl. Because despite how hard Carl was, Bob learned a lot. He's a lot better than he was back then. Now, he doesn't think he'll ever be Carl, but he's still good.
And Bob is reviewing Dave's code, and Dave's code is just as bad as Bob's was 10 years ago. So Bob calls in Dave. And he lays into Dave, "Just what the fuck do they teach in school now? Look at what you did here. You fucked it up. Don't you know about A? Or B? You have to do better."
And Bob feels good, he gave a "Carl"-style rant and now Dave will get better.
But reread how each approached their junior. Carl didn't attack Bob at all. He focused on the code itself. Bob internalized the criticisms of the code and took it personally. So when it was Bob's turn to criticize, he made it personal. Of all the lessons he was given that day, he missed the most important one.
So, you see "This commit is bad because of [X]" as polite, because you aren't the type to internalize criticism of work as criticism of you. People who do internalize it, see it as one and the same and feel that comment as "brilliant asshole".
The kind of brilliant asshole you describe, aka Bob, hangs on a bit longer because he's not bad at his core job, it's just that he has a tendency to handle people poorly.