In a vacation home, I have a Sunfire 5 channel amp that works fine and runs cool.
An Onkyo AVR is being used as a preamp but is about 5 years old and runs hot in the cabinet.
The cheapest replacement would be the lowest end AVR with 5.1 preamp outs.
So one advantage is heat reduction, which can improve longevity.
AVR's sound much better when they are working
- Rich