  GW170817, the first neutron star merger event detected by advanced LIGO/Virgo
detectors, was associated with an underluminous short duration GRB 170817A. In
this work we compare the forward shock afterglow emission of GW170817/GRB
170817A to other luminous short GRBs (sGRBs) with both a known redshift and an
afterglow emission lasting at least one day after the burst. In the rapid decay
phase, the afterglow emission of the bright sGRBs and GW170817/GRB 170817A form
a natural and continuous sequence, though separated by an observation time gap.
If viewed on-axis, the forward shock afterglow emission of GW170817/GRB 170817A
would be among the brightest ones detected so far. This provides a strong
evidence for the GW170817-like merger origin of bright sGRBs, and suggests that
the detection of the forward shock afterglow emission of most neutron star
merger events are more challenging than the case of GW170817 since usually the
mergers will be more distant and the viewing angles are plausibly higher.
