There's someone on Cactaur pulling the exact same stunt that the player the TC mentioned is, so they're at very least running the same botting script, but it wouldn't surprise me if it was actually the same individual as this type of script doesn't seem to be publicly available judging from how few people use it. While undercutting on its own isn't anything suspicious, the frequency and amount of time this individual spends doing it (They remain online for days straight at times) is what makes it obvious.
It's gotten extremely frustrating to try to sell anything now as they practically control the market for crafted gear, while multiple other botters are fighting over the infusion/food market which has been subject to so much price degradation as a result of their market flooding that it scarcely seems worth the time investment to craft for gil from the perspective of a legitimate player.
As far as the other types of bots go, they've also become a lot more numerous to the point where I've seen parties of people from the same FC going around zones in a conga line completing FATEs and there's also been a rise in "casual" botters who'll spend maybe a day bot farming something on their main account then stop for a long while until they actually need more of the stuff.