A laser sight is a huge advantage.
Meh...
I found that when it's bright enough to use my sights, it takes me just as long to find the darn laser as it would to just use the sight / optic, sometimes longer. So a laser offered me no advantage.
During limited visibility, it has been my experience that a good gun light is hard to beat, and when blasting a target with a gozillion lumens of intense white light, it's, again, just as easy to use your sights / optic. So, once again, no big advantage using a laser.
But that's for ME, not YOU!!
I met a gentleman at the range who had one on his 1911 and did quite well with it knockin' down steel and punching holes in paper. He bought it because it was easier for him to see than his sights due to vision problems. Makes sense.
Visible lasers are GREAT for dry fire training! They provide INSTANT visual feedback about fundamental errors you are making. I use a borelight laser for this purpose.
There are pro's and cons to visual lasers, and while they may not offer a significant advantage to some of us, there ARE those that they do help.
Now, IR LASERS using NODS otoh....