If you play in 4K, you can make your character less than 120 pixels tall in some cases. It's dependent on the arena/field size. on a 4K screen that's 5.5% height. This is actually problematic in early ARR dungeons where if you zoom all the way out, the actual backgrounds get in the way. But this is not a mod, this is the content that was produced before 4K was doable.
FFXIV suffers from broken windows theory.
https://en.wikipedia.org/wiki/Broken_windows_theory
In the context of a game, the more egregious modders, ACT users, and botters chase out other paying players, and we've all see this activity, if not experienced first hand from the "parser" users who harass and kick people just so they can get a better score on fflogs, to this thread with the lewd mods, and players maxing sexual advances on players who they think are into erotic role play because their client-side mods show them naked.Under the impression that a broken window left unfixed leads to more serious problems, residents begin to change the way they see their community. In an attempt to stay safe, a cohesive community starts to fall apart, as individuals start to spend less time in communal space to avoid potential violent attacks by strangers. The slow deterioration of a community as a result of broken windows modifies the way people behave when it comes to their communal space, which, in turn, breaks down community control. As rowdy teenagers, panhandlers, addicts, and prostitutes slowly make their way into a community, it signifies that the community cannot assert informal social control, and citizens become afraid that worse things will happen. As a result, they spend less time in the streets to avoid these subjects and feel less and less connected from their community if the problems persist.
ACT use is the easiest low-hanging fruit they can go after, because you've all been warned before about it by Yoshi-P. Yet people keep posting about how they use it on the official forums. SE could just turn on a silent "hook check" and track exactly what's been hooked into the memory space of the game client upon connection to the game world lobby, and one day everyone who tripped that flag get's warned, then banned if it continues. ACT actually works in exactly the same way bots do. So if they want to kill the bots, they have to kill ACT.
Texture mods are incredibly easy to detect by running checksums on the files, it takes 4 seconds per 2GB file. So it would add an entire minute to the launcher or a self-test on zone changes for someone with a SSD, or possibly several minutes for people on laptops with 5400RPM drives. But the way modders tend to get around checksum checks is by not running the official launcher, and instead running the game with outdated versions of game data, or re-patching the game data every time the game is launched. So that makes everyone suffer with additional loading time just because the modders wouldn't behave.
You guys using ACT don't even know what ACT does.
It can read/write to memory in the game client for:
Targets
Chat log
Monsters
Party members
Server time
ZoneID's
Player
So there is nothing stopping anyone from writing a bot using ACT, and it's likely bots exist that use it.