Because it doesn’t matter. It is fallacious, from an economic standpoint, to tie gross economic performance to a particular President.
Why? Because we don’t have an absolute monarch. Economic performance is tied to a plethora of variables, only some of which are influenced by politics.
And, for those that ARE involved with politics….whose politics? The President is one player, Congress is another. From a statutory standpoint, Congress has more to do with economic performance than the President does, and even in today’s situation (where Congress has ceded much of its economic responsibility to the Unitary Executive), what goes on in Congress is far more relevant, economically, than what the President does.
So, putting aside for a moment the notion that GDP growth hovering around 2%, which is where Obama was stuck, could ever be called “successful”, one could very easily take the above reasoning and credit the GOP Congress for the economic results from 2011–2017.
But, unfortunately, REALITY is a bit different. Cynically, the economy seems to perform best when Congress is gridlocked between the parties, and nothing is getting done. It seems that the corporations operate best when our government is feckless. :-)
In which case, we should be good for a few decades, because I certainly don’t see any cooperation between the parties occurring during this presidency or the next one, and probably the one after that.