And being able to table talk your way to a victory is strategy. Convincing someone to help you at a table, forming an alliance is part of the game, not a flaw. You may dislike it, but that is about your personal preferences not a flaw in game design any more than having to resource cards you put in your deck is a flaw in Cthulhu, or having to play runner vs corp is a flaw in Netrunner. They are features of the game, not flaws.
I love table talking and I play game because of player interaction. I hate the multiplayer solitare games. I am just not so big fan of how AgoT handles the multiplayer. Game shouldn't able to be decided before the game even begins (that is the situation if two friends share a table and what happened in one AGoT worlds melee tournament and this situation is easy to do in AGoT). I am ok if there are deals flying during the game and when everybody plays for themselves. Deals should affect only for the game which is played now and only the winner wins something and everybody else in finals just share the losing 2nd spot. That is reason why I like mechanisms of Vtes so much. King making is harder with that mechanism but it allows a lot of table talking and dealing. I like AGoT 1vs1 a lot tho.
Plotting ouside of the game is collusion and is forbidden under good sportsmanship rules which are part of the tourney rules in AGoT. Two people wanting to cheat at the final table is just that. Cheating. Same can be done in the final four of a joust… and has been done, at worlds even.
So it appears the problem is you have an issue with cheating. Great. Me too.