There are shooting guards, and there are guards who can shoot.
The difference is important. Shooting guard is a position, obviously, but every coach’s goal is to have two guards who can shoot the ball effectively, especially from beyond the arc. That was the hallmark of the Mavs’ 2011 title team, for example: Jason Kidd, Jason Terry, and DeShawn Stevenson were all dead-eye shooters that season, which made all the underneath stuff Dirk Nowitzki did at the elbow that much easier.
With all the scouting and analytics in today’s league, defenses are as well-prepared as they’ve ever been.