Using an unlicensed m/kb adapter masking itself as a third-party official controller to prevent detection and a possible device ban on consoles that don't natively support mouse controls... cheating or not? Survey the general gaming public, how do you think they'll respond? Do a search for Xim on any gaming forum or website and you'll find the answer pretty quickly. That moral highground you're pitching your tents on is looking pretty shaky.
Rapid-fire and anti-recoil are very lightweight mods compared to hacks and lag-switches and have little effect on the outcome. Perhaps if you loosened the stick up your arse and tried it yourself, you'd realise it ain't that bad, nor that effective after all, especially against high-level opposition.
That's exactly the same counter-argument we use to defend our Xims against the naysayers who call us cheaters, isn't it?

Besides, aren't they packing Scufs and Battle Beavers with access to the same types of "performance" mods?
This isn't a black and white issue, there are all shades of grey. If you were above reproach and insisted on an even playing field, you wouldn't be here in the first place, would you? Keep deluding yourselves into believing you're somehow better because you cheat in a different way...
If you reduce that recoil is not so big problem and is easier to aim and mid him fight start to be even easier to win.
Theoretically, yes. In reality, no.
As I've stated repeatedly, anti-recoil doesn't work particularly well because it locks you into over or undershooting if your target decides to move, which is every gamer ever in a multiplayer lobby. The brain and the hand can easily adapt, but a script programmed to move the reticle down X pixels and across Y pixels cannot. You end up trading predictable recoil for unpredictable anti-recoil, ergo it's all but useless in multi-player games, but has a place in single-player where bots lack the intelligence to dodge bullets.
The Division is a good case in point. The recoil on guns is really heavy and can be countered pretty well using anti-recoil. But, the second the opponent moves laterally or vertically is the second anti-recoil falls to pieces. So while anti-recoil is effective in single-player against a stationary target, it's really ineffective in multi-player and ultimately hurts rather than helps the player using it.
If you knew what anti-recoil actually does from experience rather than what you think it does from theorycrafting, (just like the unwashed controller masses when discussing the Xim) you'd understand that it's all but useless for multi-player, so there's absolutely no point getting your knickers in a knot. Getting used to and controlling recoil manually is by far the more effective and safer path, particularly given in-game gear mods reduce recoil and can turn semi-auto into auto-fire weapons.
So really, all you end up with is an argument against freeing up a couple of weapon slots and automating tedious button-mashing. That's quality of life stuff, not OMFGBBQ hax0r! Using the pinpoint precision and control of a mouse against the clumsiness of thumb-based analog sticks
far outweighs the minor benefit (and potentially significant detriment) of rapid-fire and/or anti-recoil

But it also doesn't guarantee the win. Stones and glass houses...
As the Xim should have taught you by now, there's a world of difference between thinking and knowing. That's why I say "live and let live" because in reality, it has close to zero effect on the outcome and any benefit is diminished the higher up the food chain you go.
Exploitation of macros is forbidden and may result in account suspension or revocation.
(https://rainbow6.ubisoft.com/siege/en-us/news/detail.aspx?c=tcm:152-249092-16&ct=tcm:148-76770-32)
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It's not a fair use since it's illegal.
It's not illegal in the slightest. Show me a single piece of legislation that outlaws the use of macros. If I can't go to jail or be sued for using a macro, then it's not "illegal".
What it is, is considered unethical and ethics vary wildly from person to person. What's right for me may be wrong for you and we'll take opposing or similar stances, depending on the topic of discussion. But using macros is very definitely and has never been "illegal".
Gaming companies provide ethical guidelines about how you're supposed to behave in their games, not legislation resulting in criminal or civil charges.
You'll also note the careful wording of Ubisoft. "Exploitation" of macros is forbidden. That doesn't mean "Use" of macros is forbidden. Exploitation is when you find a flaw in a game engine and use it to your advantage. Jitter mods in Call of Duty are one such example, head-glitching and spawn-camping are others.