It was a surprise, and a good one for me.
Yeah, as already mentioned by others, the mechanic and the concept of Barbarian class is very similar to the slayer fighter. A melee striker with good AC and defender HPs. So this is far from "broken" or "out of current game system".
And it is obvious that there is a room for armored-weapon-wielding-striker. A bunch of armor-clad warriors may have both defenders and strikers in their rank, for sure. And many of the warriors in fictions who wore armor could be classified as a striker rather than to be a defender (I think Gattsu from Berserk is a striker, maybe in heavy armor with full-blade).
Also, most fighter feats and martial-only feats are also useful for melee strikers. This new fighter is still a fighter, thus can lean them. That will double the use of many existing feats.