id have to rewatch but I believe he brought all these issues on himself
sure, but he was the heir, renly decided that he should have been the heir. when renly died, the tyrells joined the lannisters, the tyrells were bannermen to the baratheons after roberts rebellion, but decided to prop up renly so a tyrell could be on the throne, he could have made a deal with robb stark but why kiss robb stark ass or waste time fighting in the riverlands when he wanted kings landing, plus, we don't know for sure if robb would have left the riverlands anyway. So he was put in an impossible position and almost beat the lannisters anyway.
he destroyed the wildling army, giants, thenns and all, but that mostly happened off camera so he didn't get credit for that, and the one thing they don't say in the show is winter does not start north of the wall, it starts at winterfell, So the closer he got to winterfell, the worst it got, plus ramsey killing all the horses didn't help, I aint pressed about shireen's death as everybody esle, he needed more help but wasn't good at securing allies, but he was the true heir to the throne, that can't be denied