Take the long way home
A fair amount of the Fed's post-crisis "unconventional policies" have been aimed at the housing market. QEIII in particular. Often, these policies are evaluated on a very short term basis. Before and after the announcement like a pseudo event study is one popular method. Looking at what happens to rates after the policy ends is another. We've all seen charts of the last five years with vertical lines indicating the beginnings and ends of various Fed policies, with credit or blame assessed as desired.
But the basic fact about mortgage rates in this country is that they've been secularly falling. Here's a graph of the average 30 year fixed rate. Data are from Fred.
Rates are less than half what they were in 1976 when this data series begins. Rates have been steadily falling since 1982.
In other words, we've seen a steadily falling trend in mortgage rates over the last 30 years with a fair amount of short run noise around the trend.
Given that context, I think we are putting way too much emphasis on very short run movements in mortgage rates as an indicator of the effectiveness of particular Fed policies or announcements.
I also think, given mortgage rates are already at a 35 year low, that driving them down even more is not going to be a big boon to the housing market. I don't see how it helps re-financers all that much either. If you refinanced at 3.75 are you going to do it again at 3.49?
PS: Do I think the modern Fed deserves credit overall for this falling trend? Sure, just as much as they deserve blame for the ultra-high rates in the late 70s and early 80s.