The answers don't really go into what I think is the main issue: An introductory computer architecture course is generally starting from "here is what a transi

The answers don't really go into what I think is the main issue: An introductory computer architecture course is generally starting from "here is what a transistor is" and hoping to end with "here is how basic computer games work" (e.g., nand2tetris). And has about 40 hours of instruction to do it. Assembly is but a small part of the course. The ideal assembly language for such a course is one that is simple, something that you can let the interested student figure out how to implement it themselves with just a little bit of prompting. And frankly, most assembly languages aren't up to that task, even if you're willing to pretend that most of the ISA doesn't exist. x86 has issues with things like ModR/M or two-address instructions. ARM has things like r15-is-actually-the-program-counter-and-kinda-special. RISC-V coalesces most of the jump instructions into one or two instructions that is going to complete teaching subroutines in assembly (and also eschews condition codes). At the end of the day, the stuff you're covering in introductory computer architecture is very far in almost every detail from how modern computers work, and it will take several courses on top of it to actually reach those details. The most important goal of such a course isn't to teach you how they work, it's to give you the information you need to understand the explanations of how they actually work.