A big thing is the rise and rise of bullshitters. Wall to wall buzzwords and made up stories about what they did in their last job. Leetcode filters a lot, but it also filters out, just as many, if not more, people who can actually do what they say.
I think every tech-related company looked at the high bar at big tech, assumed the algorithm questions was the only signal (it's not), and have been poorly aping that ever since.
I also think a simple 20 minute discussion between a hiring candidate and an engineer simply discussing how to build something will give you better hiring signals than any Leetcode challenge.
I attended a meetup a number of years ago at a local trading firm, well known for a barrage of impossible puzzles and some simpler, like implement an order book for a matching engine. One of their senior guys did a talk on their trading system. I asked a basic question and the answer was so naive it was shocking. Maybe their best people don't do the talking.
If bullshitters are making it into your organization at the higher ranks that's something else... :(
Here is the big junior mistake, actually doing that, thinking you are going to do it better, instead of doing real work (exception: you are writing the C++ runtime).
I do agree with you about the lack of traditional CS. Whenever I am parsing anything, I first reach for a FSM, and none of all the bullshit string copy, string trim, strim unpad, string unpad in the middle. I also know enough about modern lock free algorithms to know that some 10 minute scribble and a bunch of buzzwords does not scratch the surface.
So seeing “use FSM for parsing” will obviously raise lots of an eyes will CS people, especially compiler people.
Even if it has commas in quotes, it's a comma seen in the state 'collecting text'. There is no need for anything more complicated than an FSM. Maybe there is in leetcode. One character of pushback is not a 'stack' unless you are answering a Google interviewer.
This would never come up in a Google interview and really only comes up in CS 101 (or whatever your program's first CS theory course is) when you study computational models , languages and automata for the first time. Anyone who doesn't go on to do compilers really doesn't care much about the distinction.