the story of the constantinople riots is really interesting. A foolish treaty established this unequal relationship between constantinople and venice that would later indirectly lead to the destruction of the empire through the fourth crusade and the weakening of the trade rights of its own citizens. The emperor who made that treaty was equally desperate and stupid.
The Byzantine "Empire" in 1204 was barely an empire at that point anyhow. It was essentially a rump state consisting of Greece and small portions of Anatolia.
Or, if the Byzantine Empire can be treated as an empire in 1200, the Kingdom of Hungary or the Kingdom of Poland should be treated as an empire as well.
The Venetians also essentially opened the door to the Ottomans, and the Ottomans then proceeded to dismantle the Venetian empire.