Alternative explanation for last recession

We've heard so many explanations over the past two years with regard to the causes of the most recent recession.  Some blame government incentives to raise home ownership rates as the root cause, however, research has shown that government programs at Fannie Mae likely had absolutely no impact on home ownership rates (one way or another).  Aside from these programs, home ownership rates did rise ever so slowly over the twenty years prior to the beginning of the last recession, yet in California for instance, this increase was only by about 5 percentage points over this very long horizon.  Though there was high risk individuals in the pool of homeowners who then defaulted, and a great deal of higher income speculative homeowners in California with interest only mortgages, there has been little talk about the non-recourse status of mortgages in Florida and California.  Since you can walk away from a mortgage in Florida and California without as much penalty, strategic defaulting exacerbated the downturn.  What was the real trigger for causing the recession? 

I propose that the smoking gun that initiated the recession was that construction companies over-estimated the continual increase in forecasting housing demand, producing more condo and speculative housing complexes than were demanded in 2007-2008.  This excess supply of new homes coincided with a relative drop in home purchase rates, since there was only a finite supply of home buyers, and these consumers already made their purchases.  This impetus would have pushed down house prices and set in motion the collapse that would ensue, helped by highly leveraged companies with poor enterprise risk management.

Why is this explanation so unpopular that it is never mentioned?  Perhaps it's easier to blame the poor or the greedy executives (depending on your political party) rather than construction companies who may have all estimated demand a year or two into the future before they broke ground.