Thats just not true

, a movie system will have all kinds of circuits in the signal path with a multi channel avr, it will have a big ported sub or 2, it will have a big tv clogging up the experience, speakers will have to be placed to satisfy multiple seating positions and screen view, ect ect ect.. Where a music only system, will have a super short signal path, maybe a pair of mono blocks fed by a dual mono preamp, with a pair of fast sealed subs, a small love seat of recliner placed in the sweet spot, a few pictures of various artists and or musical instruments placed around the room.