Tl;DR: It was Rob Pardo's fault. Absentee father who kept saying no, but offered zero alternatives.
Non-blaming TL;DR: Titan would have been Concord before Concord happened. Blizzard dodged a bullet by cancelling it and making Overwatch instead.
Which makes Concord a weird "Holy shit! Glad that wasn't us!" for Blizzard.
Have you tried using a bucket full of water?