I'm not advocating for more boxes (I only have one)! I'm just saying that technically it can be exactly the same thing (or sometimes even worse).
When it comes to digital, sometimes having everything crammed in close to each other may not be a good idea.
Well, in what I like, there is not a lot to cram in. but short signal paths are always a good idea.
In your post, you mention a lot of things which are not so obvious, for example: some advocate for optical connection to the source (ex: MSB) rather than I2S (which is prone to noise, since it is a high bandwidth electrical connection).
You are talking about transferring signals between two different boxes which is totally different than within one unit. With two boxes you have potential grounding/noise issues when you have electrical connections. Even with optical connections it still gets converted to I2S to go into the DAC.
Rather than argue pointlessly about the design, it's best to wait and listen.
Who's arguing?