Before Vitalik Buterin worked on Ethereum, he was involved in a project also known as Colored Coins. These were supposed to represent application like Dapps on the Bitcoin blockchain. The problem with Colored Coins was that they required nodes to backtrace every transaction in the history of the colored coin in order to make a new transaction.
Ethereum, the story of 2017
Ethereum solved this problem by separating a transaction list from the state tree. New transactions could now determine the current state by calling a concise overview of transactions rather than having to parse through every transaction. This is similar to turning on the engine to see if your car works rather than having to go through everything that ever happened to the car through crash reports, oil changes, and mileage reports to determine if you can get eggs at the supermarket today. It's just easier to check the car with the keys.
Here is a scene about Jimmy Song working on the open source Colored Coins project with Vitalik:
Here is a scene of Vitalik describing Colored Coins in 2013:
...we have come a long way in 3 years