You just need to place them on different maps. I really, really like the idea of leaving no more than 1 slot in each province. But it will not solve the main problem.
I agree it’s not a complete solution, it does however address
one of the root causes. I’m not expecting it to be the only solution needed, I’m expecting it to
help improve the ability for the weakest Guild(s) in a match to defend themselves (even more so if the idea of HQ providing Siege Camp support being implemented alongside reducing building slots outside of HQ)
The more resources and expertise a guild has available the more a guild can exponentially leverage benefits of support structures.
Siege Camps work as a balanced feature in lower leagues because those guilds don’t have the ability to leverage them to the same extent that guilds in higher leagues do. Inno had the right idea with advances needed increasing in higher leagues to account for greater guild ability, where they stopped short was in only applying that logic to a single mechanic. Had they applied it to attrition and/or support buildings or building slots available then it’d be far more effective in preventing steamrolling from sheer resources available.
It reminds me of a different game I played that had the exact same problem on a feature that was effectively GvG/GBG but presented differently. That games issue I would summarise like this:
#1 Guild: Can afford to Attack
AND Defend against everyone
#2 Guild: Can afford to Attack
AND Defend against #3 and below, can only afford to Attack
OR Defend against #1
#3 Guild and Below: Can only afford to Attack
OR Defend
Result: #2 Guild steamrolls everyone below them, #1 Guild steamrolls #2 Guild. Why? Because only one Guild is able to simultaneously attack and defend against their toughest opponent
For Inno this translates to the ability to keep going as attrition rises, and by extension the ability to remove attrition increase