That's why I wrote that I wouldn't blame you for it. Nobody in their right mind would parse post histories of anybody. But I've repeatedly talked against people screaming their minds out about how premades were the worst thing on the planet and should be removed, and how they didn't care especially for all the actual premade groups of friends going in casually without steamrolling tactics in mind. I've been of the mind since day one that the problem arises from bad design decisions.
There is jadedness because while I can myself deal perfectly fine with premades, it's becoming incredibly harder to actually delete their members because premades for one, do learn, and because deleting their key members (like the tanks) usually involves your team actually participating, else you'll just suicide your wind/meteodrive into nothing. The reason this works less and less is because people have also learned to identify premades better and they just flee immediately and I don't blame them for it. It's very pavlovian in nature: if they die from a full alliance wipe at the first engagement, they will not try again for the remainder of the game. And as said in the OP, the addition of stuff like rampage, rampart, bloodbath etc, not only makes premade players incredibly harder to pin down and kill, but it also gives them tools to facilitate the slaughter by bypassing and even outdoing the progressive AoE nerfs that SE gave to jobs over time (DRG, etc).
And this doesn't even start addressing the worst of all: being paired in the team of the premade, which is the most excruciatingly boring shit that can ever happen. That those players actually find this fun, I will never understand.
I'm asking for nothing more to make some research, but the problem is that there is literally zero way for me to do so unless leveling an actual alt on JP worlds, which is too much effort especially considering then I'd have to run a good sample of games to make sure there is different trends that I can notice.
The reason I'm being doubtful about it is because of people's natural tendency to overblow cultural differences as it's been a literally trend on those forums for ages.
You keep asking me for research and to get my own evidence yet I've yet to see anybody actually explain to me how it behaves differently on JP. All I've been told is that they don't have the problem. Then why? What is the meta they do follow? Do they also use AoE doomstacks? If not, then why? What makes it so different as what people claim? Even in the west when you get queue syncs, people don't suddenly change their meta when every team is filled with premades, because it still steamrolls as well as it does, and it also counters itself the best.
I also have my own CC experience to inform me of the small differences that EW saw between EU/NA and JP at high level, and it seemed to stem from one side lacking complete discipline and control and leaving their backline die if it meant going for kills, while the other side was at the opposite glued into a formalism that lacked creativity and initiative. The latter actually makes me wonder how JP would deal with our own meta.
I'm sorry, I am not a game designer, I don't have years to work on this, and I'm not paid to do so either. I'm giving feedback of something that I do consider problematic. I do genuinely hope that you're not here like that other forum poster to dismiss anything that doesn't come with a formal essay about the technicality of solutions to bring up to fix the issue, because that's frankly ridiculous. If anything, beware of people that instantly come up with clear, simple and evident solutions. I am also cynical enough not to expect much of it, but then I'd question why you even bother replying or posting in the first place if you're jaded enough not to care anymore at all.