Fannie Mae-No Politics (FNMA)

[NeoSunTzu]

Fannie Mae and Freddie Mac provided a willing and able buyer of MBS ...

The vast majority of what the GSEs do is buy mortgages and repackage them (securitize) to create and issue MBS which they sell to investors - pension funds, insurance companies, banks, other large investors, etc. So the "willing and able buyer" applies mostly to mortgages, not MBS. Although they do buy certain agency MBS in the secondary market it is not their bread and butter and what makes them so valuable to the mortgage market - providing mortgage market liquidity.

... and did what they were suppose to do during a financial panic.

This part is absolutely true, after the initial liquidity provided by UST - they performed as designed.