Why do certain items only drop for certain classes even if other classes can use them?

There is a rare in Ardenweald called Faeflayer. I killed him every day for like 4 months now because either handynotes or silver dragon told me that this ******** (I mean nice rare spawn) can drop a one handed axe that I could use for transmog. I'm a rogue btw.soooo I finally decided to look up the item on wowhead to see the drop rate.... I now know that only frost dks, fury and prot warriors as well as prot paladins can loot this weapon......WHY??????what's the point ? I can use one handed axes perfectly fine and even transmog it on my rogue if I would loot it on a warrior.I don't get it. can someone please explain to me how this makes sense ?