To blame the "right on liberal left" is more than a little misleading. It's not even obvious that the "right-on liberal left" even exists in the US, at least beyond a couple of fringe people. Obama is nowhere near as far left as he's sometimes made out to be. Probably close to Cameron, who -- granted -- isn't as far to the right as Tory supporters might like, but is still right of centre.
If anything, the blame lies with the (very right-wing) Republican Party, who have had eight years or so of shouting and moaning and refusing to compromise with Obama in any way whatsoever; who have enjoyed several years now of majorities in both houses of Congress but have done nothing with that; who have dragged themselves to the centre stage of US politics and then completely wasted it. They have come across as people defined not by what they stand for, but what they stand against. And the result is that a party that should have been a shoo-in for the presidency was already tearing itself apart long before Trump even got near it.
Before you blame the left's policies, it would do well to consider the right's transparent lack of them. For sure, Obama's presidency has been a bit of a damp squib, sadly -- in part because the Democrats lost control of Congress, in part because he has got many decisions just plain wrong. But Trump's success is, above all else, a symbol of the failure of the American right to offer any kind of coherent vision of what to do with its success, and its even more significant failure to be anything other than an anti-Obama party.