I used to take things too personal, or too serious, or as said here, too offensive.
It was common thing for me to FB a siege, just because I can( I wonder why I din't build walls then). It is common for players to feel a little greedy, and want to control sieges.
Bullying is also a relative term, and if we are to constrict it to levels then things will get murkey. Not all of us think PvP, and BG are what makes the game fun, so a level 80 player can just be as weak as a level 50.
With regards to leagues, well I don't really know, But it depend.
For example the is a league that has been reduced to nothings, they are always raided, Everybody hates them. They are abused, but not bullied per say.
With 1 player Vs many, I don't really know there, but I don't consider KT hitting my cattle on server 1 and 2 as Bullying, just points raids, and sieges. Just a couple of players having fun the best they can.
It also depend on the player. A socialist player can be very sensetive to offensive action ,and might not understand at all why He can just get FB at random. He is here for the communication part of the game, and that whats pull him in. They are also very desolate, and prefer to deal with the same situation again and again,, he chats at the same time like he did last time, and to the same person, about the weather,.
But BG player might not tolerate such actions. they get more fun by becoming bigger than anyone else, they are also more likely to spend. they rarely cause trouble. They are also more likely to categorize things, and players, or leagues. So bullying to then might be when they are attacked by someone/ a league not in ''their own standards''
PvP player don't pretty much care, they see it, they hit it, they care less about rank and more about domination. Deplomacy hinders them, they hate chatting, and absolutely like talking about how cool their pathfinder looks, and how much they lost last time they got hit by a FB. They can spend or could not, also dividing them into categories.
The Loner, well they hate everything, are ***holes and f**kers that will make your life miserable. they can be a/in league, but never see themselves as part of it. they are never part of anythings, they will downgrade a fort just because its donwngradeable, they will siege you, and leave 20 Mil armies they love FB, and get t buy as many as possible. They love to teleport to location and dominate evrything. you can't touch their seige. bullying to them might be somethings else. They are the kind of players that will tell you its a war game, Happy hunting and right back at you when you try to seek deplomatic resolution with. these I believe are the bullies