I never liked BFury on AM. A 5k gold investment that is only meant to make more gold, like some sort of super midas, is a waste of gold more often than not. If you can build it at 15 minutes and proceed to jungle for another 20 minutes so that you will have manta treads heart bfly on top of that bfury, sure, go for it. Too many people spend the entire game trying to farm with no boots and pers and finally finish their bfury at 30 minutes with no base around. 200+ damage an auto attack is fantastic and all but when you have 800 health you're still dead.
We actually used to have arguments about whether bfury was a good item and should be bought by ANYBODY in ANY game back in the DotA1 days. Now people feel it's basically required for heroes like AM or even BH (BH? What the hell?). I can see making one on Sven or Magnus to cap their cleave, but that 5k gold can easily be a manta style on AM which is a hell of a lot scarier in a fight.