I said it's more accessible, now. For clarity, back in the day, they released on consoles first and by the time they came to PC, there wasn't as much interest. For reference, Halo came to PC a whopping two years later from its console release. Halo 2 came nearly three years later to PC. By the time the games came to PC, there was low interest. This is coming from me, someone who played Gears of War on PC back in the day because I didn't have an Xbox. More people are asking because they're mad than because they legitimately understand the stats, and most of those "more people" are focused on the cheaters using aimbots, though I've only run into one so far in 40 hours of MP.
And though you likely realize by now, this is more about aiming than it is the overall application of KBM and controllers. The discussion of the two has never been centered around interactions and inputs, but more advantage/disadvantage in a PvP shooting-focused environment.
Coming from playing FPS on PC, it was a difficult transition for me. I used to be quite competitive in Duke Nukem 3D (aiming with keyboard, that was fun lol) in Lan setup before mouse aiming came along. It was far easier to get good with mouse aiming than later with controller. Unreal Tournament and HL Death match were my bread and butter.
My first experience with Halo multiplayer was in 4 player split screen at a friend's house. I had no clue what was going on. Quite embarrassing as my friend had been talking me up as this competitive fps player. I could hardly walk around, let alone shoot lol. But it became easier and as aim assist kept getting stronger in games I would dial the sensitivity up for quick turning and let aim assist handle the fine tuning.
Anyway, I'm no longer into competitive fps. Co-op fine, but all the crap that comes along with competition, I'll leave that to racing. Yet also in racing, I wouldn't mind at least knowing whether I got beat by a controller or a wheel. People often ask me what wheel I use, erm a DS4. Yeah, you can be competitive with a controller, but there are limits. The amount of pro players using a controller is far less than those using a wheel and peddles. Kinda odd it's the other way around with Halo? Doesn't that make the assistance a bit too strong?