Why is feeder network so long and other questions?
They needed a 7th order filter to achieve > 50dB /octave LPF, perhaps with linear phase. 

Each pole is staggered to achieve the desired Q and phase response overall and not simply  a 2nd order resonant BPF to achieve a flat group delay in the area of interest. 

You can see each pole by removing the 50R load. These will be spaced over the phase control region  possibly from fo/2 to 3fo for this filter.