Not really dead, but definitely not the "league replacement" that everyone over-hyped it to be.

• they only patch the game every month and a half.
• the game is oriented towards casual players.
• they balance the game in a bottom up style as opposed to League, which is mostly balanced around high elo and pro play... for example they gutted Roadhog because low elo players couldn't properly dodge his hook. In league bronze players suck at playing against blitzcrank. Has Riot gutted blitz because of bronze bitching? Hell no.
• Unlike most games, which have the majority of players in low elo, Blizzard has the Overwatch ranked distribution in a bell curve, with the average Overwatch player actually being Plat in rank. They do this to keep the game more rewarding to the casual player. This takes away from the competitive aspect of the game. *My final beef with the game comes from their lack of new Heroes. The game was released with only ~20 heroes, and they have only released 4 new ones since the official release a year and a half ago!