It's just a theory: Money.
AV receiver's manufacturers are saving money by relying on the subwoofers for the heavy lifting in a home theater audio sound system.
Also, shipping costs, and transformers, heatsinks, transistors, capacitors. Today it's all about streaming and computers and DSP chips and firmware updates.
So they don't need to build robust amplification anymore (20Hz-20kHz) for all eleven power amps inside their mammoths, like in some of today's Onkyo's.
The top flagship Onkyo reveiver today (11.2-channel) ... TX-RZ3100 ... has eleven internal power amps! That's like five and half stereo receivers!
But look @ the set of features! http://www.onkyo.ca/Products/model.p...class=Receiver
And with a MSRP (Cdn) price to match! $4,099.99 CAN MSRP → over four grands!
And it's less heavy than the 805 @ 43.0 lbs (19.5 kg) ... by roughly 7.9 pounds. The 805 weights 50.9 lbs (23.1 kg), and has "only" seven power amps inside.
- Onkyo TX-ZR3100 → Power Consumption: 340 W (what!)
- Onkyo TX-SR805 → Power Consumption: 9.5 A
So here you have it: Today's new TX-RZ3100 is roughly four times more expensive (MSRP) than the TX-SR805 receiver, and it weights eight pounds less!
Onkyo is making its money back from all the mistakes made since 2007. ...You know...HDMI board's replacements, wrong value resistors, excessive heat, fans that don't activate till it's too late, weak capacitors, ...all that return jazz.
Other companies are no different when it comes to weight: Denon/Marantz for example, and Yamaha too...they don't build heavy receivers in the near 100 pounds (Denon 5805 = 97 lbs), 75 pounds (Yamaha Z9 & Z11) like they used to. It's more like 25-35 pounds now. ...40 would be a monster today. We pay more for less weight and more computerization. This is the new world, the Internet, the fake news, the hackers, ...all that jazz.
New doesn't necessarily mean better than old. It means technological advancements, for the worst and the better. You need a Phd in audio/video engineering today to operate a receiver. Yesterday (70s), we just connected a pair of speakers and a turntable for sweet music to our ears, and with all the oomph we needed and without a subwoofer.
No wonder Bob Dylan won the Nobel Prize in Literature (2016):