The first incentive I remember was if you bought a house - and lived in it for 2 years - you didn't have to pay capital gains on the profit.
Each year it seemed there were more incentives - for banks, lenders, citizens etc. People were using their homes like ATM machines. Who could blame them - a house bought for $80,000 in some neighborhoods were selling for $400,000 a few years later.
Of course there wasn't really money in the house - that was an illusion until the house was sold. But people bought the idea - banks agreed and the housing market kept heating up on endless good news.
The problem: the system worked like a ponzi scheme. The first people in got out with money - lots of it. The last people lost everything. Most of us in Florida could see what was happening - anything could have caused it to burst - the situation was that unstable. So no, it wasn't oil prices .. it was government incentives that caused the mess... oil prices might have helped bring it down - but at the level it was operating, higher coffee prices could have brought it down too.
Parts of Florida and parts of California really did have a speculative real estate bubble that was very much like a ponzi scheme. But the vast majority of the country did not.
The mess in Florida and California was caused by speculation. No different than the great Tulip bubble. They weren't buying to take advantage of the incentives. They were buying because they were betting that the trend in valuations would keep going up and they'd be able to flip the houses in short order and make a mint. In a lot of cases, they weren't even living in the homes.