They're doing it to cut down on wait times.
And frankly it's quite annoying and unnecessary, please stop it or the community will rage.


Blizzard Are "Secretly" Putting Bots In Quick Play


BEEP BEEP BOOP BEEP.

For reals, though: We're not padding the Quick Play queue with bots. If you feel like another player may be using a bot, however, definitely use that right click > report feature so we can investigate. :)