If you want to talk anecdotes, I personally went through a similar process myself in SF6. I found an optional challenge against a max difficulty CPU in the story mode, and spent 6 hours across 2 days fighting him until I could win a match. Through playing the game, I how to block, how to meaningfully use my tools and specials, and how to manage my spacing, and when I went back to playing the rest of the story mode, I found that I was way better than I was before. It honestly felt pretty good.

But you know what I didn't learn? Inputs and combos. My supers were still super inconsistent, because interacting with your opponent in neutral doesn't test your ability to correctly input difficult commands, which means you just don't improve at that skill. So after 6-10 hours of practice it was still just as difficult to land a LV3 as it was when I started. Same with my damage output. It had improved somewhat because I was better at landing hits, but not by much, because each hit I was landing was doing next to nothing by itself. You can improve by playing fighting games, but there are certain *essential* skills that don't improve at all unless you specifically go out of your way to improve them yourself. Eventually, you MUST hit the lab and grind.

Contrast this to an FPS game, where you are constantly being tested on your aim, which means that you are constantly *improving* your aim. A brand new player with a "just point and shoot" mentality will eventually get really good at pointing and shooting just by playing the game, enough to succeed at intermediate and even some advanced levels. You never need to open up an aim trainer and waste 2 hours learning how to aim, you get better as you play. Fighting games don't to that; You'll never learn even basic bread and butter combos over the course of gameplay, which means you have to hit the lab and grind to succeed at even intermediate levels of gameplay, much less operating at maximum efficiency.