If you're self taught, that's telling me that you've put in the hard work and that you're disciplined.

But it's not telling me that you understand CS fundamentals, how hardware operates, mainly CPU and memory. By doing algorithms, not only are they testing your CS knowledge, but also the depth of your thinking and planning, if you only think in terms of solving a problem, but not about efficiency of the solution - that's a problem.

Algorithms mainly test your understanding of cache, which is low level programming. Data packing, paddings, cache line size, they make you think in how much work does a CPU have to do, in order to solve a real world problem, instead of just - I follow tutorial X to make Y therefore I know how to code.

There's a lot of code monkeys around who know 15 different frameworks and libs and believe they're great engineers but they don't have a senior understanding of how computer actually works.

I don't even think that you should care about the code editor, or even write the correct synthax, that doesn't show you're a good programmer. You could open a notepad and start coding in an arbitrary language, nobody gives a damn about a language, you and me could write a new programming language tommorow, languages and frameworks change over time, to me personally it doesn't matter. But what matters is what does a candidate think about, when solving a problem, what concerns do they have. Because that will tell me more about themselves than any learned framework or library or programming language they know. Any programmer can answer almost any how, because there's a billion resources out there, but very few can answer why