The actual reason was when they pushed Google+ and tried to make that the centre of Google. Everything else that had a social element had to be killed. Anything that breathed the same oxygen as plus got the boot.
Then some bonkers spokesperson for google said "oh just use quotes", which at the time did nothing even remotely the same. I loath this person for eternity, her lies, and her waving off of reporters concerns.
Thus verbatim was introduced, validating quotes weren't the same, yet which wouldn't work with date ranges, and is lame.
So goes the "professionalisn" of Google, or "screw around like uncoordinated idiots".
To say Plus was inane and destructive to Google is vastly understating. And everyone involved in Plus were buffoons.
You know, I wish could speak freely on this topic, but as a public forum, I have held back some vitriol.