Server crashed with competitive penalty

I just ended a match where the server crashed and 5 players of the other team and 4 from mine (me included) got booted to the main menu, unable to rejoin match. The Play button was titled as Rejoin Match, but clicking it did nothing. I restarted the game, only to find I got a leavers penalty and suspension.

Why do I get a suspension when the server crashes?

Because every disconnection is treated the same. More info here: Overwatch Technical Issues, SR Loss, and Leaver Penalties