I'd guess because republicans have traditionally gotten us out of dicey economic times.
The last 6 or so recessions have stopped under Republicans outside the most recent one, though despite being "technically" over I doubt many people feel it's actually over.
Reagan fixed Carters mess.
Bush Senior had a recession that he stopped after the cold war ending caused spending in that regard to fall apart. (Who's debt crisis was actually quite like the crisis today.)
Hell, even before the Sub Prime Mortgage crisis happened, Bush Junior got us out of the .com crash/9/11.
Nixon even got us out of a recession i believe.
So really... the reason people would think that is recent historical precedent. For a lot of people alive, practically any recession they've experienced as been "fixed" by a republican.
