http://nuclearcdboxafziza4mgohcwhzfjiyg6zeslnry33pepsgtur2wyeyd.onion/social/2.html
Rifles are larger and heavier, harder to maneuver if someone is very close, and can't be concealed, that's when a small handgun or knife is useful. Maybe it's also a useful backup if the rifle jams or breaks.
There are probably plenty of military articles/forums that know more about that than me, but it's important to discard the mindset of 'better' and 'worse' in a vacuum.