Combat sights have dots mostly because they cater to folks who demand them.
It is a control issue of wanting to look at the rear sight (the dots) and confirm that their alignment id "true". While that is how sight alignment is taught, it shouldn't be a goal, but rather a progression to seeing the aligned sights without looking at them.
At higher skill levels, sights are perceived as aligned and that perception cues the trigger press. This process is subconscious and frees the conscious to make the decision of when to fire on a target.
Multiple dots hinder this process and hence the development of the skill level of a shooter's ability to place accurate shots on target quickly