I wrote Big-O: how code slows as data grows to explain Big-O notation. My goal was to explain it in broad strokes for people new to the idea. It grew out of thinking I'd been doing about beginners and experts. In the comments, there was an unexpected and unfortunate real-world lesson.
An anonymous coward named "pyon" said I should be ashamed. They pointed out a detail of algorithmic analysis that I had not mentioned. It's a detail that I had never encountered before. I think it's an interesting detail, but not one that needed to be included.
Pyon is an example of a toxic expert. People like this know a lot, but they use that knowledge to separate themselves from the unwashed masses of newbs. Rather than teach, they choose to sneer from their lofty perches, lamenting the state of the world around them, filled as it is with People Who Don't Want To Learn.
The important skill pyon and other toxic experts are missing is how to connect with people. They could use their knowledge to teach, but it's more important to them to separate themselves from others. Points of correctness are useless without points of connection.
Toxic experts care more about making distinctions between people to elevate themselves than they do about helping people. Beware: they are everywhere you look in the tech world. It's easy to run into them when you are trying to learn. Ignore them. They don't know you, and they don't know what you can do.
Pyon is fixated on a particular detail of algorithmic analysis, and feels that it is essential to understanding Big-O. I can tell you is that I am doing fine in my 30-year career, and I had never heard that particular detail. My Big-O piece wasn't meant to be exhaustive. There are entire books written about algorithmic notation. I even wrote at the end, "There's much more to algorithm analysis if you want to get into the true computer science aspects of it, but this is enough for working developers."
But pyon can't see the forest for the trees. Experts have spent a lot of time and energy learning what they know. They love their knowledge. They wouldn't have been able to get where they are without a passion for the subject. But sometimes they have a hard time seeing how people can be successful without that well-loved knowledge. They've lost sight of what it means to be a beginner, and what beginners need to learn.
Toxic experts will latch onto a particular skill and decide that it is essential. For them, that skill is a marker dividing Those-Who-Know from Those-Who-Don't. These shibboleths vary from expert to expert. In the current case, it's a detail of algorithmic analysis. I've seen other toxic experts insist that it's essential to know C, or assembly language, or recursion and pointers, and so on.
I'm not saying those aren't good things to know. The more you know, the better. Every one of these topics will be useful. But they are not essential. You can do good work without them. You certainly don't deserve to be spat upon.
The ultimate irony is that while pyon and other toxic experts are bemoaning the state of the industry because of missing knowledge, they are highlighting the main skill gap the tech industry needs to fix: empathy.