From a caddie's perspective, technology undoubtedly helps to speed up play. I've used one for several years now and find that by the time your golfer gets to the ball, a good caddie will have the yardage for the shot. I also use a GPS watch. It comes in handy several time per round for distances to the front/back of the green, as well as the distance to the green when your player has a blind shot and you cannot shoot the pin.
When a golfer does not have a caddie, the rangefinder can actually slow you down. The time it takes to the rangefinder out of the bag/cart, aim & shoot, then return it to the bag/cart can be time consuming. The GPS watch, on the other hand, is very simple: look at your wrist, look at the pin, pick a club. (Inevitably the GPS watch can speed up play, but a scratch golfer might object because the watch distances might be off by a few yards, because a rangefinder's output is more exact.)
For the past 50 years all I have ever needed is the 150 yard stakes. Even when I first got a rangefinder for caddying, I never used it when I played. Now that I have the GPS watch, besides giving me distances, it allows me to more accurately evaluate the distances that I hit my clubs. So, I really enjoy having the watch.
Returning back to the original premise: "What if Laser/GPS were banned?" Having coached high school golf for more than a decade, I know that the younger golfer would have a harder time adjusting because they are more reliant on technology now than they were even five or ten years ago. Also, reading a number of these postings and from personal experience, it seems as if the veteran golfers would be affected the least because we grew up with only the 150 markers.