Blizzard has made it very clear from the start that what they are doing with Heroes of the Storm sets it apart for typical MOBAs. In fact, it can’t even be technically called a MOBA since that involves only 2 goals, kill enemy heroes and destroy their base.
Heroes of the Storm, on the other hand, is more of an objective focused game rather than a PvP one. The developers keep emphasizing on the importance of objectives to take the edge in a match resulting in your triumph.
Every map has its own unique main objective besides several optional objectives, which stay the same across all maps. Optional objectives provide you with mercenaries and other such neutral characters, which can provide you with additional Manpower to attack an enemy base.
The main objectives can range from getting one of your team’s heroes buffed up to a Dragon hero which serves as a really powerful ally for a short amount of time, to controlling pirate ships which can do massive damage to the enemy base in order for you to win the game.
Since the game is very different from the typical MOBAs players are used to, it becomes difficult to for many of them to focus on objective, which is why most of the players are still only focusing on PvP.
If one was to visit the official forums, they would notice players talking about their team mates totally ignoring the objective resulting in a loss for the team.
In my opinion, it is a really good move by Blizzard, revolutionizing the genre in this way when every other game is just copying the original formula and putting a coat of paint over it to create a new game. It will, however, take players time to get used to the usual tried and tested formula.