The precedent exists. (too much Dual Wield too much Martial Arts)
It's not really the same.
Too much DW/Martial doesn't hurt those same stats, but it hurts dps because of the tp/delay calculations.
Here someone is saying (based on what, exactely?) that too much TH hurts your TH+ proc.
How do you even come up with an idea like this? Do you just wake up one day and start believing that?
Tomorrow I can wake up and say that I think using Frailty together with Languor on the same target will make the enemy immune to TH which will stay capped at TH0?
I mean you can't go around and make baseless claims like that, can you? >____>
@Boshi
SE gave us official drop rate % boost for all TH up to TH14, did they not?
I mean if you don't believe SE it's another story of course, but they gave us those numbers and if we are to believe them I'd say TH has more importance than we gave it credit for, for content where it actually works, of course.
What we know is that there's something more about TH level up procs.
We know the level up rate is ~6% chance per melee hit, as long as your TH level is as high as the current level applied to the target. The lower you go, the lower that number goes down.
This has been tested (small tests, not conclusive but good enough) for TH up to TH8 thanks to /THF, Feint, Bounty Shot and other means.
This is how it works up to TH9 and it's pretty widely accepted by the community afaik.
What's unknown is: what happens above that?
In theory TH8 is the "cap" that you can apply instantly on a target, meaning that equipping more TH than that, won't allow you to instantly apply an effect higher than TH8.
But does this limitation apply to the level up proc system as well?
Some tests (unconclusive, alas) seemed to hint that raising your TH slightly raises your chances of getting a level up proc.
Which makes sense, basically the same rule that applies for all the levels up to TH8, also applies past that. It makes more sense if you ask me, and the TH8 is "just" a limitation for the initial hit, not for the level up proc system.
The culprit that skews the data we gathered so far imho is another.
We know for instance that if you hit for 0 damage, you won't be able to get a level up proc.
I think there are similar limitations at play here.
Probably multihit attacks and offhand hits won't be able to proc level up, meaning that -likely- only main hit base hits are able to proc the level up.
So for a more relevant test, you would need to remove your offhand, remove all your multiattck gear (sadly you can't remove the TA from traits, which will make the gathered data a bit hard to handle) and then measure the rate.
I'm pretty confident that we would find out that TH above TH8 does indeed help with getting TH level up procs more frequently
in theory.
In reality it won't be a big help because:
1) You're gonna have lotsa MA and OH hits, which won't proc
2) The level up rate is still very low (~6% under the best condition, for a single hit out of each of your attack rounds)
3) In the time it would take you to get TH up to TH14, you can probably kill the same NM 3 times with TH9, and three TH9 kills will probably produce a better overall drop rate than one TH14 kill.
So tl;dr imho yes, additional TH above TH8 probably does help with the level up rate, but because of what we said the increase is very minimal and highly unpractical, so don't bother with it.