When flying above the haze layer you can see distant buildups
for literally hundreds of miles if they are high enough. This picture
was also taken at 6,500' just skimming the top of the haze layer in Georgia.
The buildups popping up in the distance were just beginning to build
and were about 40 miles away. Note the smaller buildups below the
haze layer in the foreground
Flying above the haze layer makes it easier to decide which way to deviate to avoid buildups in the distance. The clear view above the haze layer also makes it easier to spot traffic, and there is far less traffic at these altitudes. I have sometimes flown between Atlanta and Miami without seeing a single aircraft near my cruising altitude.