While some azaleas are petite, Southern Indica hybrids such as 'Formosa' can grow as big as a bus. The short picket fence in front tames the azalea just a bit while also framing the blossoms during the week or so the shrub is in bloom.
After that, the fence will help define space. You can create the same sort of effect with other vigorous spring-flowering shrubs such as forsythias, spiraeas, loropetalums, mock oranges, flowering quinces, and weigelas.