Think of a weather radar like a flashlight. As the light beam travels from the flashlight it widens and more faint with distance.
The weather radar beam also widens and weakens with distance. At 36 miles a radar beam is already 6,000 feet wide. At 75 miles the beam is closer to 12,000 feet wide.
As the beam widens and weakens resolution significantly drops. The same storm when scanned at 18 miles from the radar site will have 4 times the resolution of a radar 75 miles from the radar site.
Areas closer to the Shoals before the Early Warning Radar Network had poor resolution at street level. The previous closest radar sites: Columbus in Mississippi and Hytop in Jackson County were far enough away that street level tracking was coarse and low-res.
Resolution matters when you are tracking at street level. A closer radar site can track the finer details of dangerous weather. Small changes in rotating winds could mean better placement of tornadoes or damaging winds at street level. When tracking heavy rain, the higher resolution will be able to pick out areas at higher risk for flooding.