(Some could argue that its still kind of dismissed, since one basically has to build their deck around it if they intend to use it.) Most Pendulum monsters at the time were archetype-specific, and thus very few could be added into any deck without issue
Cards like Phytotitan, Malignus, and Daemogoth Titan are all great targets to be sacrificed to Ziatora in order to deal some real damage, The treasures generated by Ziatora also enable you to work some artifact synergies into your deck, or even pull off a Revel in Riches win
His effect is quite simple but always effective towards getting the cards you need in your hand
For the rest of this turn after this card resolves, you cannot Special Summon monsters, except Zombie monsters
Conversely, when you cast Prosperity for X=4, you lose a card (Prosperity itself), but you gain four cards, for a net gain of three