If it's just one repeater you don't need a rotator
Quite true. However, I thought we were talking about "significantly more repeaters". I guess we never defined "significantly".
From my location, if I look out 10 miles there are 5 repeaters. At 20 miles, 10 repeaters. At 30 miles, 18. At 50 miles, 39. So as I look further out there are more repeaters and they are not all in the same direction. A rotator might help to single out just one.
There was a interesting demonstration of "line of sight" communication, when I was working in Germany. We dealt with ground mapping radar systems that were onboard F4s. The plane had film on board, but they didn't want to wait for the plane to land and the film to be processed. So they used a data link. The air base was on the highest hill in the area and the antenna (25' dish) was on top of the PIF (Photographic Interpretation Facility) building. The planes were flying at about 35,000'. Usually, we would lose their signal when they were about 90 miles away, but sometimes we were able to track them to 110 miles out. So even though there were no obstructions, the atmosphere often limited our range.