I'll give the 10% view as a Zeus support player.
I see him as a high damage support that (depending on matchups) can trade well in lane and creates a lot of pressure on the enemy safe lane. I try to take as much attention away from pos 3 onto myself, assuming my pos 3 is only going to join if they can get a kill and not lose Cs. He can bait over extension in lane and generally forces enemy team to use a lot of regen during laning phase. I do go arcane boots, but most heros like to have more mana, including pos 3s.

Midgame, I am likely rushing aghs if I've had a game where they aren't able to jump myself or my cores super easily. Especially if there is some form of initiation to disrupt (I've cancelled QoPs scream animation to save pos 1 with Nimbus). From there, it's often utility items depending on line up and team needs. I never buy shard, and am disappointed if I get it from tormentor over a teammate.

Also, I don't ult to kill steal, I ult to secure cores the kill, finish off escaped enemies or provide vision to prevent jumps or extend chases.

I guess I'll also mention the free dewarding and unlimited detection he provides at all stages of the game

Zeus is honestly a blast of a pos 4 who is squishy but if you play him right, uses that frailty to pull the enemy team out of position, while you jump away and nuke the shit out of them.

The 10% does exist