A few things to note:
-Leeching bans are global, so when you were banned from one server for leeching you're banned from all official servers. You weren't specifically banned from multiple servers, that's just how leeching bans work to prevent, you know, leeching.
-Even if you weren't there to see the verbal warnings from an admin, getting kicked represents a (more serious) warning to change your behavior or be banned.
-Leeching is increasing your level & gold without contributing to your team. It goes against the spirit of the game and CAN hurt others even if you originally go AFK in an empty server. Example: you afk in an empty server, and a few people join, hoping to get a game going. Since you're still AFK you're contributing nothing to your team & the players on your team get sick of fighting short-handed, so they quit, once again leaving the server empty. If you were there to contribute people might stay in the server longer, and it could become more populated.
-Leeching is against the rules explicitly, so even if you think it's not hurting anyone you're still breaking the rules & admins are tasked with enforcing the rules.
It's good that you're being honest about leeching, but it also seems clear that you don't understand why what you did is wrong. I hope the above helps clear it up and I hope you stop leeching in the future, otherwise your bans will likely increase in length or eventually become permanent.
Anyways, your ban is now expired, so I'm locking the thread.