There are various options to consider actually.
1.) Rebalancing of the raids (ARR + potentially HW)
While the least likely due to the amount of effort required to rescale the raid, it will have the most profound impact based on the potency-per-second difference from now to back in ARR. Our HP is also a lot more consistent with the addition of Vitality on all gear pieces, making a boss like Bone Dragon and his Platinal adds a minimal threat. This alone may not be enough though, leading to...
2.) Item level CAP
A much easier to implement feature as it exists throughout the entire game already. The minimum item level for the CT raids are 40 item levels below the respective Coil Raid cap that was obtainable since then (LotA min 50, 1st Coil max 90; ST min 70, 2nd Coil max 110; WoD min 90, 3rd Coil max 130).
Considering there is currently no cap, we are essentially doing Labyrinth of the Ancients with 80 item levels above the intended difficulty and Syrcus Tower still by a whopping 60. Higher even, as 135 is the item level maximum for Lv50.
3.) Dynamic item level requirements
Hardly a shocker, these exist as well. While currently statically implemented every major patch with Mentor Roulette, a dynamic version is not out of the question. Essentially lift the item level and unlock requirements based on your job's current level to continue being able to do Alliance Raid roulette on that job. Fundamentally:
- per level backet (50, 60, 70, etc) require minimum 1 of your current level bracket and all previous unlocked
- per unlocked duty, raise minimum required item level based on the highest currently unlocked
This is essentially a small-scale database check on your unlocked content and searching for "max" on "minimum item level" in your available duties.
4.) EXP adjustments
Should all else fail, an adjustment to EXP and/or other rewards are an option. However I wouldn't leave it at "just increase for all other content", I'd go as far as saying "reduce it for LotA and ST" if they remain in the powercrept state they are currently in.
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I'll be honest, it is a hot mess and I won't say it is "easy to just do it'" given I work in a similar work environment, but it is definitely within their scope and within reason to do SOMETHING about it.