I think it's all about personal taste.
I also prefer separates for EVERYTHING - speakers, subs, pre-pro, amps, etc.
All my subwoofers have Separate External Amps, not internal amps.
But Separates isn't for everyone. Some people even prefer to put almost everything - amps, processors, and EQ/DSP all inside the speakers!
Can you imagine what happens if some newbie bought speakers with everything inside them and when they plug in the speakers, there's no sound?
Is it the speaker drivers? Speaker wire? Amps inside the speakers? Processor inside the speakers? EQ/DSP inside the speakers?
Now I'm not saying that putting all the amps, processor, EQ, DSP, etc. inside the speaker is the same thing as putting processor and amps inside the AVR.
But the question is, which is worse?
A. Putting amps, processors, EQ/DSP inside the speakers?
B. Putting amps and processors inside the AVR?
I would think that # A is worse than # B since now you're putting the ENTIRE AVR inside the speaker.
So then we're not just talking Separates vs AVR. We're now talking about Separates vs AVR-Inside-Speakers.