More likely is the simple fact the current strategy (or whichever version you wish to choose) has not been very successful....and we remain mired in an eighteen year old war that continues to cost lives, limbs, and money.
Trump ran on the promise to get us untangled in these kinds of affairs.
Look back to the very start of the Afghanistan War....Special Ops Teams with Air Support and related assistance defeated the hostile forces. Very small numbers of very capable troops on the ground with lots of sophisticated support did very well.
Then....the Conventional forces arrived and we know the rest of that story.
You also recall Trump asked the Military and Intelligence Communities what the end goal was for Afghanistan and Syria and was not pleased with the mumbling and non-committal responses.
Also....he is not a politician in the standard definition and is neither a Liberal or Conservative but rather is simply a pragmatist who comes from the business world and not prior elected offices.
He is results oriented and not happy at all with mealy mouthed half assed answers.
Washington and the Media are quite comfortable in their ruts....and hate being shaken up and made to justify their lack of success over the years.
The Kurdish area of Syria that is at risk is very small....and in the long game is not worth the risk to our national security interests in that region.
Our military likes to leave large numbers of boots on the ground in these affairs and thus increasing the likelihood of drawn out involvements.
At least this time Mattis resigned....and did so on his own with no encouragement from the President.
The last time he got out of step with a President....Obama fired him from CentCom.
Obama did not like being asked questions about his Iranian policy.
I am of the belief Trump is trying to extricate the US Military from these seemingly never ending conflicts and reducing our presence....military or civilian in the process.
The military has talked of much the same strategy as Prinz but using Spec Ops troops and local forces augmented by non-uniformed government personnel.