remember red dot limits you to 50-100m... unless you get some really expansive one like Docter or trijicon.. with 1 MOA..... my burris is 4 MOA.. and it almost covers 50% of the target at 100m.. so if you go further... i think it might cover the whole target...when scope... brings the target right to you.... and lets you have an easier shot placement...
No, a red dot does not "limit" you to 50-100m.
I don't have any problem hitting 300m silhouettes with my 4moa Aimpoint on my AR. You just need to know which part of the dot to hold on which part of the target.
Any limit is operator imposed.