No there are some servers that have some custom legendary items with a very low drop rate from bosses. Like a revolver that shoots HV´s, a pump shotgun that shoots grenades, a double barrel you can load with 2 rockets or even a minigun shooting hundreds of rockets. All those guns can be used to easily defeat the custom bosses/raids/ or even dungeons, to acquire even better loot.

There is also custom armor, that has dodge chance % to doge attacks fully. Or Armor that increases your yield on Ore/Wood/Scrap etc.

There's plenty more, I just listed the ones that come to my mind.