Then again, if his powers are really that grand, it seems highly doubtful that The Three-Eyed Raven would appear to Bran in the first place as opposed to a faster-moving greenseer like Jojen Reed to get this White Walker prep going ASAP.
To understand why the Three-Eyed Raven is so important, perhaps the somewhat baffling decision in choosing Bran holds the key as to why.
Those pondering the last point ask an excellent question as one might assume that the Three-Eyed Raven is more than capable of stopping the White Walker invasion on his own.
If Bran Stark can go back in time and ruin Hodor’s life, then can’t he as The Three-Eyed Raven just go back as far as it takes to defeat the White Walkers and impact the past in some way to prevent a second coming from happening?