I used a red dot sight back in the early 90's. I found that it increased my ability to quickly acquire my target quicker. There was no magnification, so I could shoot with both eyes open which increased my field of vision. I could adjust for distance based on my stereo vision and adjust my marker angle to accomplish distance accuracy. After while, I no longer need the sight because my muscle memory kicked in and allowed me to acquire a target by just looking and pointing.
I had used a magnified scope for a while. It did not work well for a paintball marker because you couldn't determine distance accurately. I did find it was great for sighting and finding long range targets that you normally couldn't see because of heavy camouflage or shadows.
Overall, I could still see using a red dot or occluded sight on a paintball marker, especially to enhance the milsim look.
Except for the Automag in front, its usually the man behind the equipment that counts.