I hope you did not take my question as a personal “attack” on you. That was not the intent and the furthest from my mind. If I offended, I apologize. That was never my intention.
I see now that you are speaking about YOUR personal experience in using the RDS, and the difficulty you encountered. Not necessarily of RDS in general.
The reason I asked is because I often see similar claims, and they are usually based on second hand experience, or faulty information.
I can say that my experience differs. I wear trifocals (progressive lenses), and I encountered that no matter how I tried, I could never get a clear sight alignment/picture because focusing on the front sight post was impossible. I even had problems with focusing to read the instrument panel when I was driving, the glasses fixed that, but could not fix the iron sights issue. The front sight was always a blur. That is the main reason I decided to try out the RDS.
At the beginning I had the same issue, the dot looked like a starburst, was difficult to find, and was slower for targeting. So I started to look for information about it, and watched a ton of videos. What I found was that I was doing it wrong. When you have a red/green dot, you DO NOT focus on the dot at all. You place your eye sight focus on the target, and then super impose the dot peripherally.
With both eyes open, go ahead and point to a light switch within your view. Now focus on the light switch only. Can you still see your finger pointing (hovering within view) at the switch? It should look like your finger “vanishes”, but you can still see it. That is exactly how the RDS works, but because it is a bright light, it does not vanish. Whatever the dot is on top of is where the bullet will land (after you zero the sight of course). If you catch yourself focusing on the dot you will get that starburst effect again. RDS also “requires” that you keep both eyes open. Particularly when you are getting used to how they work. That is the biggest problem when coming from an iron sight focus. That is the reason it requires practice, practice, practice.
To train myself to remain target focused, I put a piece of tape on the sight in order to block my view through the sight window, but not to obstruct the side with the dot. That forces your sight to focus on the target, because if you focus on the dot you will only see the dot and an occluded view. If that happens, focus on the target again. I used dry fire for about two weeks, until finding the dot was easy, and I remained target focused.
I hope you are able to find a workable solution to your sight issues. I know that for me the RDS was the only way that I could keep enjoying shooting. Without it, the iron sight issues just made shooting very unenjoyable and I would probably have stopped doing it altogether.