I agree reliability is the important point, but you are making general statements that should only apply in same situations. In most applications, power amps in AVRs won't likely fail before the preamp/dac section. The few exceptions were likely 99.999% due to people abusing them, such as pushing the output, and their hearing beyond their limits.
If you browse forums you will see most failures of AVRs have to do with the HDMI and protective circuitry acting up, rarely related to the internal amps no matter how many channels.
For the recent models such as the C30, if one pair it with a 3 channel 200/300W 8/4 ohms power amp and use the internal amps for the surround and height/Atmos channels, it will perform better than the AV7706 paired with those Monolith amps.
I suspect that I would be guilty of pushing a receiver beyond its limits. A massive orchestra in the pit, plus 150 member opera chorus and assorted brass players would probably do for a receiver if I had one.
In any case a receiver can not drive my system as my speakers system was not designed to be driven from one. So the issue is moot as far as I'm concerned.
I have found the AVPs to be reliable. My second one had an early failure due to a bad voltage regulator, but that was fixed and it worked for many years As far as I know it still does as it is in my storage pile. The next two AVPs are still in daily use, after I think 14 years. The 7705 is four and half years old, almost. Talking of which I was surprised they could improve the unit with firmware updates. When new it could produce some potentially speaker busting thumps, but these were banished with the first firmware update.
For the initial period the SNR was not all I hoped for. You could not hear noise in any program, but you could hear a faint hiss at the listening positions in a quiet room, whereas all those 9 Quad amps made no noise you could hear in the room. After updates, you can no longer hear the hiss in the room, but you can hear it if your stick your ear in the speaker. I have to assume they could change the gain structure through the firmware somehow. Or may be the solid state devices just settled down.
I have no complaint against the unit at this time. The distortion is so low, that it is irrelevant, especially compared to any speaker.
So I don't see any need to buy the 7706. I am certain I would hear no difference. So now it is a race to see who dies first, me or the 7705.
The other issue is that you can give maximal protection to an AVP which contains the fragile circuits vulnerable to power issues, but you can't a receiver, because of the power amps. I feel this has to impact longevity. Protection is something I engineer in. Only the power amps are protected just by surge protections at the residence power entry.
So currently I enjoy really good sound, and I have never heard the system get even near its limits, let alone over.
So my view is that AVPs have a definite place in no holes barred systems.
The last issue is that not having rack mounting is a deal breaker for me. A unit weighing what that C30 does needs to be able to be mounted in a 19" rack. With all those connections, being able to get behind it is essential. If not, it is a nightmare installation right from the start.